Refactor tests and implementations for various indicators

- Updated RsiIndicatorTests to ensure proper initialization and state checks.
- Added new tests for Rsx, Vel, and Adosc indicators to validate behavior under iterative corrections and edge cases (NaN, Infinity).
- Enhanced Bessel indicator tests and implementation with consistent formatting.
- Improved Ema and Pwma implementations by ensuring proper handling of values.
- Introduced mock classes for charting to facilitate testing without dependencies.
- Ensured all indicators produce consistent results across different modes of operation.
- Cleaned up code formatting and added missing commas for better readability.

docs/momentum-test-implementation-plan.md

@@ -0,0 +1,902 @@
+# Momentum Indicators Test Implementation Plan
+
+> **Objective:** Bring all 13 momentum indicators to full compliance with testprotocol.md
+
+## Executive Summary
+
+- **Total Missing Tests:** ~72 tests across 12 indicators
+- **Estimated Effort:** 4-6 hours
+- **Priority:** Start with MACD (most deficient), end with VEL (closest to compliant)
+
+---
+
+## Phase 1: Critical Deficiencies (MACD, BOP)
+
+### 1.1 MACD - Add 10 Tests
+
+**File:** `lib/momentum/macd/Macd.Tests.cs`
+
+```csharp
+// ADD THESE TESTS:
+
+[Fact]
+public void Constructor_InvalidParameters_ThrowsArgumentException()
+{
+    Assert.Throws<ArgumentException>(() => new Macd(0, 26, 9));
+    Assert.Throws<ArgumentException>(() => new Macd(12, 0, 9));
+    Assert.Throws<ArgumentException>(() => new Macd(12, 26, 0));
+    Assert.Throws<ArgumentException>(() => new Macd(26, 12, 9)); // fast >= slow
+}
+
+[Fact]
+public void Calc_IsNew_AcceptsParameter()
+{
+    var macd = new Macd(12, 26, 9);
+    var gbm = new GBM();
+    var series = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 49; i++)
+        macd.Update(series.Close[i], isNew: true);
+    
+    var val1 = macd.Update(series.Close[49], isNew: true);
+    var val2 = macd.Update(new TValue(DateTime.UtcNow, series.Close[49].Value + 1), isNew: true);
+    
+    Assert.NotEqual(val1.Value, val2.Value);
+}
+
+[Fact]
+public void Calc_IsNew_False_UpdatesValue()
+{
+    var macd = new Macd(12, 26, 9);
+    var gbm = new GBM();
+    var series = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 49; i++)
+        macd.Update(series.Close[i]);
+    
+    var val1 = macd.Update(series.Close[49], isNew: true);
+    var val2 = macd.Update(new TValue(series.Close[49].Time, series.Close[49].Value + 5), isNew: false);
+    
+    Assert.Equal(val1.Time, val2.Time);
+    Assert.NotEqual(val1.Value, val2.Value);
+}
+
+[Fact]
+public void IterativeCorrections_RestoreToOriginalState()
+{
+    var macd = new Macd(12, 26, 9);
+    var gbm = new GBM();
+    var series = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 50; i++)
+        macd.Update(series.Close[i]);
+    
+    var originalValue = macd.Last;
+    
+    for (int m = 0; m < 5; m++)
+    {
+        var modified = new TValue(series.Close[49].Time, series.Close[49].Value + m);
+        macd.Update(modified, isNew: false);
+    }
+    
+    var restored = macd.Update(series.Close[49], isNew: false);
+    Assert.Equal(originalValue.Value, restored.Value, 1e-9);
+}
+
+[Fact]
+public void Reset_ClearsState()
+{
+    var macd = new Macd(12, 26, 9);
+    var gbm = new GBM();
+    var series = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < series.Count; i++)
+        macd.Update(series.Close[i]);
+    
+    macd.Reset();
+    
+    Assert.Equal(0, macd.Last.Value);
+    Assert.False(macd.IsHot);
+}
+
+[Fact]
+public void IsHot_BecomesTrueWhenBufferFull()
+{
+    var macd = new Macd(12, 26, 9);
+    var gbm = new GBM();
+    var series = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    Assert.False(macd.IsHot);
+    
+    for (int i = 0; i < series.Count; i++)
+    {
+        macd.Update(series.Close[i]);
+        if (i >= 40) break; // Should be hot by warmup
+    }
+    
+    Assert.True(macd.IsHot);
+}
+
+[Fact]
+public void NaN_Input_UsesLastValidValue()
+{
+    var macd = new Macd(12, 26, 9);
+    var gbm = new GBM();
+    var series = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 40; i++)
+        macd.Update(series.Close[i]);
+    
+    var result = macd.Update(new TValue(DateTime.UtcNow, double.NaN));
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void Infinity_Input_UsesLastValidValue()
+{
+    var macd = new Macd(12, 26, 9);
+    var gbm = new GBM();
+    var series = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 40; i++)
+        macd.Update(series.Close[i]);
+    
+    var result = macd.Update(new TValue(DateTime.UtcNow, double.PositiveInfinity));
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void AllModes_ProduceSameResult()
+{
+    var gbm = new GBM(seed: 123);
+    var series = gbm.Fetch(200, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    // 1. Batch Mode
+    var batchMacd = new Macd(12, 26, 9);
+    var batchResult = batchMacd.Update(series.Close);
+    double expected = batchResult.Last.Value;
+    
+    // 2. Span Mode
+    var spanOutput = new double[series.Count];
+    Macd.Calculate(series.Close.Values, spanOutput, 12, 26);
+    double spanResult = spanOutput[^1];
+    
+    // 3. Streaming Mode
+    var streamMacd = new Macd(12, 26, 9);
+    for (int i = 0; i < series.Count; i++)
+        streamMacd.Update(series.Close[i]);
+    double streamResult = streamMacd.Last.Value;
+    
+    // 4. Eventing Mode
+    var pubSource = new TSeries();
+    var eventMacd = new Macd(pubSource, 12, 26, 9);
+    for (int i = 0; i < series.Count; i++)
+        pubSource.Add(series.Close[i]);
+    double eventResult = eventMacd.Last.Value;
+    
+    Assert.Equal(expected, spanResult, 9);
+    Assert.Equal(expected, streamResult, 9);
+    Assert.Equal(expected, eventResult, 9);
+}
+
+[Fact]
+public void SpanBatch_ValidatesInput()
+{
+    double[] source = [1, 2, 3, 4, 5];
+    double[] output = new double[5];
+    double[] wrongSize = new double[3];
+    
+    Assert.Throws<ArgumentException>(() => Macd.Calculate(source, wrongSize, 12, 26));
+    Assert.Throws<ArgumentException>(() => Macd.Calculate(source, output, 0, 26));
+    Assert.Throws<ArgumentException>(() => Macd.Calculate(source, output, 12, 0));
+}
+```
+
+### 1.2 BOP - Add 9 Tests
+
+**File:** `lib/momentum/bop/Bop.Tests.cs`
+
+```csharp
+// ADD THESE TESTS:
+
+[Fact]
+public void Calc_IsNew_AcceptsParameter()
+{
+    var bop = new Bop();
+    var bar1 = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+    var bar2 = new TBar(DateTime.UtcNow, 15, 25, 10, 20, 100);
+    
+    bop.Update(bar1, isNew: true);
+    var val1 = bop.Last.Value;
+    
+    bop.Update(bar2, isNew: true);
+    var val2 = bop.Last.Value;
+    
+    Assert.NotEqual(val1, val2);
+}
+
+[Fact]
+public void Calc_IsNew_False_UpdatesValue()
+{
+    var bop = new Bop();
+    var bar1 = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+    var bar2 = new TBar(DateTime.UtcNow, 10, 25, 5, 20, 100);
+    
+    var val1 = bop.Update(bar1, isNew: true);
+    var val2 = bop.Update(bar2, isNew: false);
+    
+    Assert.Equal(val1.Time, val2.Time);
+    Assert.NotEqual(val1.Value, val2.Value);
+}
+
+[Fact]
+public void IterativeCorrections_RestoreToOriginalState()
+{
+    var bop = new Bop();
+    var bar = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+    
+    var originalValue = bop.Update(bar, isNew: true);
+    
+    for (int i = 0; i < 5; i++)
+    {
+        var modified = new TBar(bar.Time, bar.Open, bar.High + i, bar.Low, bar.Close, bar.Volume);
+        bop.Update(modified, isNew: false);
+    }
+    
+    var restored = bop.Update(bar, isNew: false);
+    Assert.Equal(originalValue.Value, restored.Value, 1e-9);
+}
+
+[Fact]
+public void Reset_ClearsState()
+{
+    var bop = new Bop();
+    var bar = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+    
+    bop.Update(bar);
+    bop.Reset();
+    
+    Assert.Equal(0, bop.Last.Value);
+}
+
+[Fact]
+public void IsHot_BecomesTrueWhenBufferFull()
+{
+    var bop = new Bop();
+    
+    Assert.False(bop.IsHot);
+    
+    var bar = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+    bop.Update(bar);
+    
+    Assert.True(bop.IsHot); // BOP is hot immediately (no warmup needed)
+}
+
+[Fact]
+public void NaN_Input_UsesLastValidValue()
+{
+    var bop = new Bop();
+    var bar1 = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+    var barNaN = new TBar(DateTime.UtcNow, double.NaN, 20, 5, 15, 100);
+    
+    bop.Update(bar1);
+    var result = bop.Update(barNaN);
+    
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void Infinity_Input_UsesLastValidValue()
+{
+    var bop = new Bop();
+    var bar1 = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+    var barInf = new TBar(DateTime.UtcNow, double.PositiveInfinity, 20, 5, 15, 100);
+    
+    bop.Update(bar1);
+    var result = bop.Update(barInf);
+    
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void AllModes_ProduceSameResult()
+{
+    var gbm = new GBM(seed: 123);
+    var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    // 1. Batch Mode
+    var batchResult = Bop.Batch(bars);
+    double expected = batchResult.Last.Value;
+    
+    // 2. Span Mode
+    var spanOutput = new double[bars.Count];
+    Bop.Calculate(bars.Open.Values, bars.High.Values, bars.Low.Values, bars.Close.Values, spanOutput);
+    double spanResult = spanOutput[^1];
+    
+    // 3. Streaming Mode
+    var streamBop = new Bop();
+    for (int i = 0; i < bars.Count; i++)
+        streamBop.Update(bars[i]);
+    double streamResult = streamBop.Last.Value;
+    
+    Assert.Equal(expected, spanResult, 9);
+    Assert.Equal(expected, streamResult, 9);
+}
+
+[Fact]
+public void SpanBatch_ValidatesInput()
+{
+    double[] open = [1, 2, 3];
+    double[] high = [2, 3, 4];
+    double[] low = [0, 1, 2];
+    double[] close = [1.5, 2.5, 3.5];
+    double[] output = new double[3];
+    double[] wrongSize = new double[2];
+    
+    Assert.Throws<ArgumentException>(() => Bop.Calculate(open, high, low, close, wrongSize));
+}
+```
+
+---
+
+## Phase 2: Medium Deficiencies (DMX, CFB)
+
+### 2.1 DMX - Add 7 Tests
+
+**File:** `lib/momentum/dmx/Dmx.Tests.cs`
+
+```csharp
+// ADD THESE TESTS:
+
+[Fact]
+public void Constructor_InvalidParameters_ThrowsArgumentException()
+{
+    Assert.Throws<ArgumentException>(() => new Dmx(0));
+    Assert.Throws<ArgumentException>(() => new Dmx(-1));
+}
+
+[Fact]
+public void IterativeCorrections_RestoreToOriginalState()
+{
+    var dmx = new Dmx(14);
+    var gbm = new GBM();
+    var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 50; i++)
+        dmx.Update(bars[i]);
+    
+    var originalValue = dmx.Last;
+    
+    for (int m = 0; m < 5; m++)
+    {
+        var modified = new TBar(bars[49].Time, bars[49].Open, bars[49].High + m, bars[49].Low - m, bars[49].Close, bars[49].Volume);
+        dmx.Update(modified, isNew: false);
+    }
+    
+    var restored = dmx.Update(bars[49], isNew: false);
+    Assert.Equal(originalValue.Value, restored.Value, 1e-9);
+}
+
+[Fact]
+public void IsHot_BecomesTrueWhenBufferFull()
+{
+    var dmx = new Dmx(14);
+    var gbm = new GBM();
+    var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    Assert.False(dmx.IsHot);
+    
+    for (int i = 0; i < bars.Count; i++)
+    {
+        dmx.Update(bars[i]);
+        if (dmx.IsHot) break;
+    }
+    
+    Assert.True(dmx.IsHot);
+}
+
+[Fact]
+public void NaN_Input_UsesLastValidValue()
+{
+    var dmx = new Dmx(14);
+    var gbm = new GBM();
+    var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 30; i++)
+        dmx.Update(bars[i]);
+    
+    var nanBar = new TBar(DateTime.UtcNow, double.NaN, double.NaN, double.NaN, double.NaN, 100);
+    var result = dmx.Update(nanBar);
+    
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void Infinity_Input_UsesLastValidValue()
+{
+    var dmx = new Dmx(14);
+    var gbm = new GBM();
+    var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 30; i++)
+        dmx.Update(bars[i]);
+    
+    var infBar = new TBar(DateTime.UtcNow, double.PositiveInfinity, double.PositiveInfinity, 0, 100, 100);
+    var result = dmx.Update(infBar);
+    
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void AllModes_ProduceSameResult()
+{
+    var gbm = new GBM(seed: 123);
+    var bars = gbm.Fetch(200, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    // 1. Batch Mode
+    var batchResult = Dmx.Batch(bars, 14);
+    double expected = batchResult.Last.Value;
+    
+    // 2. Streaming Mode
+    var streamDmx = new Dmx(14);
+    for (int i = 0; i < bars.Count; i++)
+        streamDmx.Update(bars[i]);
+    double streamResult = streamDmx.Last.Value;
+    
+    Assert.Equal(expected, streamResult, 9);
+}
+
+[Fact]
+public void SpanBatch_ValidatesInput()
+{
+    // Add if DMX has span API
+}
+```
+
+### 2.2 CFB - Add 5 Tests
+
+**File:** `lib/momentum/cfb/Cfb.Tests.cs`
+
+```csharp
+// ADD THESE TESTS:
+
+[Fact]
+public void Constructor_InvalidParameters_ThrowsArgumentException()
+{
+    Assert.Throws<ArgumentException>(() => new Cfb(Array.Empty<int>()));
+    Assert.Throws<ArgumentException>(() => new Cfb(new[] { 0, 10 }));
+    Assert.Throws<ArgumentException>(() => new Cfb(new[] { -1, 10 }));
+}
+
+[Fact]
+public void IterativeCorrections_RestoreToOriginalState()
+{
+    var cfb = new Cfb();
+    var gbm = new GBM();
+    var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 50; i++)
+        cfb.Update(new TValue(bars.Close.Times[i], bars.Close.Values[i]));
+    
+    var originalValue = cfb.Last;
+    
+    for (int m = 0; m < 5; m++)
+    {
+        var modified = new TValue(bars.Close.Times[49], bars.Close.Values[49] + m);
+        cfb.Update(modified, isNew: false);
+    }
+    
+    var restored = cfb.Update(new TValue(bars.Close.Times[49], bars.Close.Values[49]), isNew: false);
+    Assert.Equal(originalValue.Value, restored.Value, 1e-9);
+}
+
+[Fact]
+public void IsHot_BecomesTrueWhenBufferFull()
+{
+    var cfb = new Cfb(new[] { 5, 10 });
+    var gbm = new GBM();
+    var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < bars.Count; i++)
+    {
+        cfb.Update(new TValue(bars.Close.Times[i], bars.Close.Values[i]));
+        if (cfb.IsHot) break;
+    }
+    
+    Assert.True(cfb.IsHot);
+}
+
+[Fact]
+public void NaN_Input_UsesLastValidValue()
+{
+    var cfb = new Cfb();
+    var gbm = new GBM();
+    var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 30; i++)
+        cfb.Update(new TValue(bars.Close.Times[i], bars.Close.Values[i]));
+    
+    var result = cfb.Update(new TValue(DateTime.UtcNow, double.NaN));
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void Infinity_Input_UsesLastValidValue()
+{
+    var cfb = new Cfb();
+    var gbm = new GBM();
+    var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 30; i++)
+        cfb.Update(new TValue(bars.Close.Times[i], bars.Close.Values[i]));
+    
+    var result = cfb.Update(new TValue(DateTime.UtcNow, double.PositiveInfinity));
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void AllModes_ProduceSameResult()
+{
+    var gbm = new GBM(seed: 123);
+    var bars = gbm.Fetch(200, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    // 1. Batch Mode
+    var batchResult = Cfb.Batch(bars.Close);
+    double expected = batchResult.Last.Value;
+    
+    // 2. Span Mode
+    var spanOutput = new double[bars.Count];
+    Cfb.Batch(bars.Close.Values.ToArray(), spanOutput);
+    double spanResult = spanOutput[^1];
+    
+    // 3. Streaming Mode
+    var streamCfb = new Cfb();
+    for (int i = 0; i < bars.Count; i++)
+        streamCfb.Update(new TValue(bars.Close.Times[i], bars.Close.Values[i]));
+    double streamResult = streamCfb.Last.Value;
+    
+    Assert.Equal(expected, spanResult, 9);
+    Assert.Equal(expected, streamResult, 9);
+}
+```
+
+---
+
+## Phase 3: Standard Deficiencies (ADX, ADXR, AO, APO, Aroon, AroonOsc)
+
+These 6 indicators all have the same pattern of missing tests. Create a template:
+
+### Template for TBar-based Indicators (ADX, ADXR, AO, Aroon, AroonOsc)
+
+```csharp
+// ADD THESE 6 TESTS TO EACH:
+
+[Fact]
+public void IterativeCorrections_RestoreToOriginalState()
+{
+    var indicator = new [IndicatorName](period);
+    var gbm = new GBM();
+    var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 50; i++)
+        indicator.Update(bars[i]);
+    
+    var originalValue = indicator.Last;
+    
+    for (int m = 0; m < 5; m++)
+    {
+        var modified = new TBar(bars[49].Time, bars[49].Open, bars[49].High + m, bars[49].Low - m, bars[49].Close, bars[49].Volume);
+        indicator.Update(modified, isNew: false);
+    }
+    
+    var restored = indicator.Update(bars[49], isNew: false);
+    Assert.Equal(originalValue.Value, restored.Value, 1e-9);
+}
+
+[Fact]
+public void IsHot_BecomesTrueWhenBufferFull()
+{
+    var indicator = new [IndicatorName](period);
+    var gbm = new GBM();
+    var bars = gbm.Fetch(200, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    Assert.False(indicator.IsHot);
+    
+    for (int i = 0; i < bars.Count; i++)
+    {
+        indicator.Update(bars[i]);
+        if (indicator.IsHot) break;
+    }
+    
+    Assert.True(indicator.IsHot);
+}
+
+[Fact]
+public void NaN_Input_UsesLastValidValue()
+{
+    var indicator = new [IndicatorName](period);
+    var gbm = new GBM();
+    var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 40; i++)
+        indicator.Update(bars[i]);
+    
+    var nanBar = new TBar(DateTime.UtcNow, double.NaN, double.NaN, double.NaN, double.NaN, 100);
+    var result = indicator.Update(nanBar);
+    
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void Infinity_Input_UsesLastValidValue()
+{
+    var indicator = new [IndicatorName](period);
+    var gbm = new GBM();
+    var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 40; i++)
+        indicator.Update(bars[i]);
+    
+    var infBar = new TBar(DateTime.UtcNow, double.PositiveInfinity, double.PositiveInfinity, 0, 100, 100);
+    var result = indicator.Update(infBar);
+    
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void AllModes_ProduceSameResult()
+{
+    var gbm = new GBM(seed: 123);
+    var bars = gbm.Fetch(200, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    // 1. Batch Mode
+    var batchResult = [IndicatorName].Batch(bars, period);
+    double expected = batchResult.Last.Value;
+    
+    // 2. Streaming Mode
+    var streamIndicator = new [IndicatorName](period);
+    for (int i = 0; i < bars.Count; i++)
+        streamIndicator.Update(bars[i]);
+    double streamResult = streamIndicator.Last.Value;
+    
+    Assert.Equal(expected, streamResult, 9);
+}
+
+[Fact]
+public void SpanBatch_ValidatesInput()
+{
+    // Implement if indicator has Span API
+}
+```
+
+### Template for TValue-based Indicator (APO)
+
+Similar pattern but uses `series.Close[i]` instead of `bars[i]`.
+
+---
+
+## Phase 4: Minor Deficiencies (RSX, VEL)
+
+### 4.1 RSX - Add 4 Tests
+
+```csharp
+[Fact]
+public void IterativeCorrections_RestoreToOriginalState()
+{
+    var rsx = new Rsx(14);
+    var gbm = new GBM();
+    var series = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 50; i++)
+        rsx.Update(new TValue(series.Close.Times[i], series.Close.Values[i]));
+    
+    var originalValue = rsx.Last;
+    
+    for (int m = 0; m < 5; m++)
+    {
+        var modified = new TValue(series.Close.Times[49], series.Close.Values[49] + m);
+        rsx.Update(modified, isNew: false);
+    }
+    
+    var restored = rsx.Update(new TValue(series.Close.Times[49], series.Close.Values[49]), isNew: false);
+    Assert.Equal(originalValue.Value, restored.Value, 1e-9);
+}
+
+[Fact]
+public void IsHot_BecomesTrueWhenBufferFull()
+{
+    var rsx = new Rsx(14);
+    var gbm = new GBM();
+    var series = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    Assert.False(rsx.IsHot);
+    
+    for (int i = 0; i < series.Count; i++)
+    {
+        rsx.Update(new TValue(series.Close.Times[i], series.Close.Values[i]));
+        if (rsx.IsHot) break;
+    }
+    
+    Assert.True(rsx.IsHot);
+}
+
+[Fact]
+public void Infinity_Input_UsesLastValidValue()
+{
+    var rsx = new Rsx(14);
+    rsx.Update(new TValue(DateTime.UtcNow, 100));
+    var result = rsx.Update(new TValue(DateTime.UtcNow, double.PositiveInfinity));
+    
+    Assert.False(double.IsInfinity(result.Value));
+    Assert.InRange(result.Value, 0, 100);
+}
+
+[Fact]
+public void AllModes_ProduceSameResult()
+{
+    int period = 14;
+    var gbm = new GBM(seed: 123);
+    var series = gbm.Fetch(200, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    // 1. Batch Mode
+    var batchResult = Rsx.Batch(series.Close, period);
+    double expected = batchResult.Last.Value;
+    
+    // 2. Span Mode
+    var spanOutput = new double[series.Count];
+    Rsx.Batch(series.Close.Values.ToArray(), spanOutput, period);
+    double spanResult = spanOutput[^1];
+    
+    // 3. Streaming Mode
+    var streamRsx = new Rsx(period);
+    for (int i = 0; i < series.Count; i++)
+        streamRsx.Update(new TValue(series.Close.Times[i], series.Close.Values[i]));
+    double streamResult = streamRsx.Last.Value;
+    
+    // 4. Eventing Mode
+    var pubSource = new TSeries();
+    var eventRsx = new Rsx(pubSource, period);
+    for (int i = 0; i < series.Count; i++)
+        pubSource.Add(new TValue(series.Close.Times[i], series.Close.Values[i]));
+    double eventResult = eventRsx.Last.Value;
+    
+    Assert.Equal(expected, spanResult, 9);
+    Assert.Equal(expected, streamResult, 9);
+    Assert.Equal(expected, eventResult, 9);
+}
+```
+
+### 4.2 VEL - Add 4 Tests
+
+```csharp
+[Fact]
+public void IterativeCorrections_RestoreToOriginalState()
+{
+    var vel = new Vel(10);
+    var gbm = new GBM();
+    var series = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 50; i++)
+        vel.Update(series.Close[i]);
+    
+    var originalValue = vel.Last;
+    
+    for (int m = 0; m < 5; m++)
+    {
+        var modified = new TValue(series.Close[49].Time, series.Close[49].Value + m);
+        vel.Update(modified, isNew: false);
+    }
+    
+    var restored = vel.Update(series.Close[49], isNew: false);
+    Assert.Equal(originalValue.Value, restored.Value, 1e-9);
+}
+
+[Fact]
+public void NaN_Input_UsesLastValidValue()
+{
+    var vel = new Vel(10);
+    var gbm = new GBM();
+    var series = gbm.Fetch(20, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 15; i++)
+        vel.Update(series.Close[i]);
+    
+    var result = vel.Update(new TValue(DateTime.UtcNow, double.NaN));
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void Infinity_Input_UsesLastValidValue()
+{
+    var vel = new Vel(10);
+    var gbm = new GBM();
+    var series = gbm.Fetch(20, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    for (int i = 0; i < 15; i++)
+        vel.Update(series.Close[i]);
+    
+    var result = vel.Update(new TValue(DateTime.UtcNow, double.PositiveInfinity));
+    Assert.True(double.IsFinite(result.Value));
+}
+
+[Fact]
+public void AllModes_ProduceSameResult()
+{
+    int period = 10;
+    var gbm = new GBM(seed: 123);
+    var series = gbm.Fetch(200, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    
+    // 1. Batch Mode
+    var batchResult = Vel.Batch(series.Close, period);
+    double expected = batchResult.Last.Value;
+    
+    // 2. Span Mode
+    var spanOutput = new double[series.Count];
+    Vel.Batch(series.Close.Values.ToArray().AsSpan(), spanOutput.AsSpan(), period);
+    double spanResult = spanOutput[^1];
+    
+    // 3. Streaming Mode
+    var streamVel = new Vel(period);
+    for (int i = 0; i < series.Count; i++)
+        streamVel.Update(series.Close[i]);
+    double streamResult = streamVel.Last.Value;
+    
+    // 4. Eventing Mode
+    var pubSource = new TSeries();
+    var eventVel = new Vel(pubSource, period);
+    for (int i = 0; i < series.Count; i++)
+        pubSource.Add(series.Close[i]);
+    double eventResult = eventVel.Last.Value;
+    
+    Assert.Equal(expected, spanResult, 9);
+    Assert.Equal(expected, streamResult, 9);
+    Assert.Equal(expected, eventResult, 9);
+}
+
+[Fact]
+public void SpanBatch_ValidatesInput()
+{
+    double[] source = [1, 2, 3, 4, 5];
+    double[] output = new double[5];
+    double[] wrongSize = new double[3];
+    
+    Assert.Throws<ArgumentException>(() => Vel.Batch(source.AsSpan(), wrongSize.AsSpan(), 3));
+    Assert.Throws<ArgumentException>(() => Vel.Batch(source.AsSpan(), output.AsSpan(), 0));
+    Assert.Throws<ArgumentException>(() => Vel.Batch(source.AsSpan(), output.AsSpan(), -1));
+}
+```
+
+---
+
+## Implementation Checklist
+
+### Phase 1 (Priority: Critical)
+- [ ] MACD.Tests.cs - Add 10 tests
+- [ ] BOP.Tests.cs - Add 9 tests
+
+### Phase 2 (Priority: High)
+- [ ] DMX.Tests.cs - Add 7 tests
+- [ ] CFB.Tests.cs - Add 5 tests
+
+### Phase 3 (Priority: Medium)
+- [ ] ADX.Tests.cs - Add 6 tests
+- [ ] ADXR.Tests.cs - Add 6 tests
+- [ ] AO.Tests.cs - Add 6 tests
+- [ ] APO.Tests.cs - Add 6 tests
+- [ ] Aroon.Tests.cs - Add 6 tests
+- [ ] AroonOsc.Tests.cs - Add 6 tests
+
+### Phase 4 (Priority: Low)
+- [ ] RSX.Tests.cs - Add 4 tests
+- [ ] VEL.Tests.cs - Add 4 tests
+
+---
+
+## Verification Steps
+
+After implementing all tests:
+
+1. Run all tests: `dotnet test lib/QuanTAlib.Tests.csproj`
+2. Verify no regressions in existing tests
+3. Check test coverage meets targets
+4. Update docs/validation.md with compliance status

lib/core/AbstractBase.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.CompilerServices;
 
 namespace QuanTAlib;
 
@@ -36,6 +37,7 @@ public abstract class AbstractBase : ITValuePublisher
     /// <summary>
     /// Helper to invoke the Pub event.
     /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
     protected void PubEvent(TValue value, bool isNew = true)
     {
         Pub?.Invoke(this, new TValueEventArgs { Value = value, IsNew = isNew });

lib/core/ringbuffer/RingBuffer.Tests.cs

@@ -719,4 +719,175 @@ public class RingBufferTests
         Assert.Equal(21.666666666666668, buffer.Average, 1e-10);
         Assert.NotEqual(avgBeforeCorrection, buffer.Average);
     }
+
+    [Fact]
+    public void Snapshot_CapturesCurrentState()
+    {
+        var buffer = new RingBuffer(5);
+
+        buffer.Add(10.0);
+        buffer.Add(20.0);
+        buffer.Add(30.0);
+
+        buffer.Snapshot();
+
+        // Modify buffer after snapshot
+        buffer.Add(40.0);
+
+        Assert.Equal(4, buffer.Count);
+        Assert.Equal(100.0, buffer.Sum); // 10 + 20 + 30 + 40
+    }
+
+    [Fact]
+    public void Restore_ReturnsToSnapshotState()
+    {
+        var buffer = new RingBuffer(5);
+
+        buffer.Add(10.0);
+        buffer.Add(20.0);
+        buffer.Add(30.0);
+
+        buffer.Snapshot();
+        double sumBeforeModification = buffer.Sum;
+        int countBeforeModification = buffer.Count;
+
+        // Modify buffer after snapshot
+        buffer.Add(40.0);
+        Assert.Equal(4, buffer.Count);
+
+        // Restore to snapshot state
+        buffer.Restore();
+
+        Assert.Equal(countBeforeModification, buffer.Count);
+        Assert.Equal(sumBeforeModification, buffer.Sum);
+    }
+
+    [Fact]
+    public void Snapshot_Restore_WithWrapping()
+    {
+        var buffer = new RingBuffer(3);
+
+        buffer.Add(10.0);
+        buffer.Add(20.0);
+        buffer.Add(30.0);
+
+        buffer.Snapshot();
+
+        // Add value that causes wrap
+        buffer.Add(40.0);
+        Assert.Equal(90.0, buffer.Sum); // 20 + 30 + 40
+
+        buffer.Restore();
+
+        Assert.Equal(60.0, buffer.Sum); // 10 + 20 + 30
+        Assert.Equal(30.0, buffer.Newest);
+    }
+
+    [Fact]
+    public void RecalculateSum_CorrectsDrift()
+    {
+        var buffer = new RingBuffer(5);
+
+        buffer.Add(10.0);
+        buffer.Add(20.0);
+        buffer.Add(30.0);
+
+        double recalculated = buffer.RecalculateSum();
+
+        Assert.Equal(60.0, recalculated);
+        Assert.Equal(60.0, buffer.Sum);
+    }
+
+    [Fact]
+    public void RecalculateSum_AfterMultipleOperations()
+    {
+        var buffer = new RingBuffer(3);
+
+        // Simulate many operations that could accumulate floating-point drift
+        for (int i = 0; i < 100; i++)
+        {
+            buffer.Add(i * 0.1);
+        }
+
+        double recalculated = buffer.RecalculateSum();
+
+        // Should be equal (or very close) since we're using exact values
+        Assert.Equal(recalculated, buffer.Sum);
+    }
+
+    [Fact]
+    public void StartIndex_EmptyBuffer_ReturnsZero()
+    {
+        var buffer = new RingBuffer(5);
+
+        Assert.Equal(0, buffer.StartIndex);
+    }
+
+    [Fact]
+    public void StartIndex_PartiallyFilled_ReturnsZero()
+    {
+        var buffer = new RingBuffer(5);
+
+        buffer.Add(10.0);
+        buffer.Add(20.0);
+
+        Assert.Equal(0, buffer.StartIndex);
+    }
+
+    [Fact]
+    public void StartIndex_FullBuffer_ReturnsHead()
+    {
+        var buffer = new RingBuffer(3);
+
+        buffer.Add(10.0);
+        buffer.Add(20.0);
+        buffer.Add(30.0);
+        buffer.Add(40.0); // Wraps
+
+        // StartIndex should point to oldest element
+        Assert.True(buffer.StartIndex >= 0 && buffer.StartIndex < buffer.Capacity);
+        Assert.Equal(20.0, buffer.Oldest);
+    }
+
+    [Fact]
+    public void Indexer_NegativeIndexViaFromEnd_ThrowsWhenOutOfBounds()
+    {
+        var buffer = new RingBuffer(5);
+
+        buffer.Add(10.0);
+        buffer.Add(20.0);
+        buffer.Add(30.0);
+
+        // ^4 when count=3 should throw
+        Assert.Throws<ArgumentOutOfRangeException>(() => _ = buffer[^4]);
+    }
+
+    [Fact]
+    public void CopyTo_InsufficientDestinationBuffer_Behavior()
+    {
+        var buffer = new RingBuffer(5);
+
+        buffer.Add(10.0);
+        buffer.Add(20.0);
+        buffer.Add(30.0);
+
+        var dest = new double[2]; // Too small
+
+        // This will throw IndexOutOfRangeException since we're copying 3 elements to size-2 array
+        Assert.Throws<ArgumentException>(() => buffer.CopyTo(dest, 0));
+    }
+
+    [Fact]
+    public void CopyTo_StartIndexOutOfRange_Behavior()
+    {
+        var buffer = new RingBuffer(5);
+
+        buffer.Add(10.0);
+        buffer.Add(20.0);
+
+        var dest = new double[5];
+
+        // Starting at index 4 with 2 elements should fail
+        Assert.Throws<ArgumentException>(() => buffer.CopyTo(dest, 4));
+    }
 }

lib/core/simd/SimdExtensions.Tests.cs

@@ -805,4 +805,191 @@ public class SimdScalarFallbackTests
         Assert.Equal(42.5, min);
         Assert.Equal(42.5, max);
     }
+
+    // Additional edge case tests
+    [Fact]
+    public void DotProduct_ContainsNaN_PropagatesNaN()
+    {
+        double[] a = [1.0, double.NaN, 3.0];
+        double[] b = [4.0, 5.0, 6.0];
+        double result = SimdExtensions.DotProduct(a, b);
+        Assert.True(double.IsNaN(result));
+    }
+
+    [Fact]
+    public void DotProduct_ContainsInfinity_PropagatesCorrectly()
+    {
+        double[] a = [1.0, double.PositiveInfinity, 3.0];
+        double[] b = [4.0, 5.0, 6.0];
+        double result = SimdExtensions.DotProduct(a, b);
+        Assert.True(double.IsPositiveInfinity(result));
+    }
+
+    [Fact]
+    public void Add_ContainsNaN_PropagatesNaN()
+    {
+        double[] left = [1.0, double.NaN, 3.0];
+        double[] right = [4.0, 5.0, 6.0];
+        double[] result = new double[3];
+
+        SimdExtensions.Add(left, right, result);
+
+        Assert.Equal(5.0, result[0]);
+        Assert.True(double.IsNaN(result[1]));
+        Assert.Equal(9.0, result[2]);
+    }
+
+    [Fact]
+    public void Subtract_ContainsNaN_PropagatesNaN()
+    {
+        double[] left = [10.0, double.NaN, 30.0];
+        double[] right = [1.0, 2.0, 3.0];
+        double[] result = new double[3];
+
+        SimdExtensions.Subtract(left, right, result);
+
+        Assert.Equal(9.0, result[0]);
+        Assert.True(double.IsNaN(result[1]));
+        Assert.Equal(27.0, result[2]);
+    }
+
+    [Fact]
+    public void ContainsNonFinite_NegativeInfinityAtStart_ReturnsTrue()
+    {
+        double[] data = [double.NegativeInfinity, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0];
+        var span = new ReadOnlySpan<double>(data);
+        Assert.True(span.ContainsNonFinite());
+    }
+
+    [Fact]
+    public void ContainsNonFinite_NegativeInfinityAtEnd_ReturnsTrue()
+    {
+        double[] data = [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, double.NegativeInfinity];
+        var span = new ReadOnlySpan<double>(data);
+        Assert.True(span.ContainsNonFinite());
+    }
+
+    [Fact]
+    public void VarianceSIMD_SingleElement_ReturnsNaN()
+    {
+        double[] data = [42.5];
+        var span = new ReadOnlySpan<double>(data);
+        Assert.True(double.IsNaN(span.VarianceSIMD()));
+    }
+
+    [Fact]
+    public void StdDevSIMD_SingleElement_ReturnsNaN()
+    {
+        double[] data = [42.5];
+        var span = new ReadOnlySpan<double>(data);
+        Assert.True(double.IsNaN(span.StdDevSIMD()));
+    }
+
+    [Fact]
+    public void StdDevSIMD_EmptySpan_ReturnsNaN()
+    {
+        var span = ReadOnlySpan<double>.Empty;
+        Assert.True(double.IsNaN(span.StdDevSIMD()));
+    }
+
+    [Fact]
+    public void SumSIMD_SingleElement_ReturnsElement()
+    {
+        double[] data = [42.5];
+        var span = new ReadOnlySpan<double>(data);
+        Assert.Equal(42.5, span.SumSIMD());
+    }
+
+    [Fact]
+    public void AverageSIMD_SingleElement_ReturnsElement()
+    {
+        double[] data = [42.5];
+        var span = new ReadOnlySpan<double>(data);
+        Assert.Equal(42.5, span.AverageSIMD());
+    }
+
+    [Fact]
+    public void DotProduct_SingleElement_ReturnsProduct()
+    {
+        double[] a = [3.0];
+        double[] b = [4.0];
+        Assert.Equal(12.0, SimdExtensions.DotProduct(a, b));
+    }
+
+    [Fact]
+    public void DotProduct_TwoElements_ReturnsCorrect()
+    {
+        double[] a = [2.0, 3.0];
+        double[] b = [4.0, 5.0];
+        // 2*4 + 3*5 = 8 + 15 = 23
+        Assert.Equal(23.0, SimdExtensions.DotProduct(a, b));
+    }
+
+    [Fact]
+    public void Add_SingleElement_Works()
+    {
+        double[] left = [5.0];
+        double[] right = [3.0];
+        double[] result = new double[1];
+
+        SimdExtensions.Add(left, right, result);
+
+        Assert.Equal(8.0, result[0]);
+    }
+
+    [Fact]
+    public void Subtract_SingleElement_Works()
+    {
+        double[] left = [5.0];
+        double[] right = [3.0];
+        double[] result = new double[1];
+
+        SimdExtensions.Subtract(left, right, result);
+
+        Assert.Equal(2.0, result[0]);
+    }
+
+    [Fact]
+    public void Add_EmptyArrays_Works()
+    {
+        double[] left = [];
+        double[] right = [];
+        double[] result = [];
+
+        SimdExtensions.Add(left, right, result); // Should not throw
+
+        Assert.Empty(result);
+    }
+
+    [Fact]
+    public void Subtract_EmptyArrays_Works()
+    {
+        double[] left = [];
+        double[] right = [];
+        double[] result = [];
+
+        SimdExtensions.Subtract(left, right, result); // Should not throw
+
+        Assert.Empty(result);
+    }
+
+    [Fact]
+    public void Add_ResultTooSmall_ThrowsArgumentException()
+    {
+        double[] left = [1.0, 2.0, 3.0];
+        double[] right = [4.0, 5.0, 6.0];
+        double[] result = new double[2]; // Too small
+
+        Assert.Throws<ArgumentException>(() => SimdExtensions.Add(left, right, result));
+    }
+
+    [Fact]
+    public void Subtract_ResultTooSmall_ThrowsArgumentException()
+    {
+        double[] left = [1.0, 2.0, 3.0];
+        double[] right = [4.0, 5.0, 6.0];
+        double[] result = new double[2]; // Too small
+
+        Assert.Throws<ArgumentException>(() => SimdExtensions.Subtract(left, right, result));
+    }
 }

lib/core/tbar/TBar.Tests.cs

@@ -345,5 +345,156 @@ public class TBarTests
             var bar2 = new TBar(12346, 100, 110, 90, 105, 1000);
 
             Assert.True(bar1 != bar2);
-    }
+        }
+
+        // Additional edge case tests
+        [Fact]
+        public void Constructor_WithLocalDateTime_ConvertsToUtc()
+        {
+            var localDateTime = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Local);
+            var bar = new TBar(localDateTime, 100, 110, 90, 105, 1000);
+
+            // AsDateTime should return UTC
+            Assert.Equal(DateTimeKind.Utc, bar.AsDateTime.Kind);
+            Assert.Equal(localDateTime.ToUniversalTime().Ticks, bar.Time);
+        }
+
+        [Fact]
+        public void Constructor_WithUnspecifiedDateTime_ConvertsToUtc()
+        {
+            var unspecifiedDateTime = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Unspecified);
+            var bar = new TBar(unspecifiedDateTime, 100, 110, 90, 105, 1000);
+
+            // Should be converted to UTC
+            Assert.Equal(DateTimeKind.Utc, bar.AsDateTime.Kind);
+        }
+
+        [Fact]
+        public void DefaultTBar_HasZeroValues()
+        {
+            var bar = default(TBar);
+
+            Assert.Equal(0, bar.Time);
+            Assert.Equal(0.0, bar.Open);
+            Assert.Equal(0.0, bar.High);
+            Assert.Equal(0.0, bar.Low);
+            Assert.Equal(0.0, bar.Close);
+            Assert.Equal(0.0, bar.Volume);
+        }
+
+        [Fact]
+        public void TBar_WithNaN_HandlesGracefully()
+        {
+            var bar = new TBar(12345, double.NaN, 110, 90, 105, 1000);
+
+            Assert.True(double.IsNaN(bar.Open));
+            Assert.True(double.IsNaN(bar.O.Value));
+            Assert.True(double.IsNaN(bar.OHL3)); // Uses Open
+            Assert.True(double.IsNaN(bar.OC2));  // Uses Open
+            Assert.True(double.IsNaN(bar.OHLC4)); // Uses Open
+        }
+
+        [Fact]
+        public void TBar_WithInfinity_HandlesGracefully()
+        {
+            var bar = new TBar(12345, 100, double.PositiveInfinity, 90, 105, 1000);
+
+            Assert.True(double.IsPositiveInfinity(bar.High));
+            Assert.True(double.IsPositiveInfinity(bar.H.Value));
+            Assert.True(double.IsPositiveInfinity(bar.HL2)); // Uses High
+        }
+
+        [Fact]
+        public void TBar_WithMaxValue_HandlesGracefully()
+        {
+            var bar = new TBar(12345, double.MaxValue, double.MaxValue, double.MinValue, 105, 1000);
+
+            Assert.Equal(double.MaxValue, bar.Open);
+            Assert.Equal(double.MaxValue, bar.High);
+            Assert.Equal(double.MinValue, bar.Low);
+            // HL2 calculation with extreme values
+            Assert.True(double.IsFinite(bar.HL2) || double.IsInfinity(bar.HL2));
+        }
+
+        [Fact]
+        public void TBar_WithEpsilon_HandlesGracefully()
+        {
+            var bar = new TBar(12345, double.Epsilon, double.Epsilon, double.Epsilon, double.Epsilon, double.Epsilon);
+
+            Assert.Equal(double.Epsilon, bar.Open);
+            Assert.Equal(double.Epsilon, bar.Close);
+            Assert.True(bar.HL2 > 0);
+        }
+
+        [Fact]
+        public void HL2_WithNegativeValues_CalculatesCorrectly()
+        {
+            var bar = new TBar(0, -100, -90, -110, -95, 1000);
+
+            Assert.Equal(-100.0, bar.HL2); // (-90 + -110) / 2
+        }
+
+        [Fact]
+        public void OHLC4_WithNegativeValues_CalculatesCorrectly()
+        {
+            var bar = new TBar(0, -100, -90, -110, -100, 1000);
+
+            Assert.Equal(-100.0, bar.OHLC4); // (-100 + -90 + -110 + -100) / 4
+        }
+
+        [Fact]
+        public void ImplicitConversion_ToTValue_PreservesTimeAndClose()
+        {
+            long time = 12_345_678_901_234_567;
+            var bar = new TBar(time, 100, 110, 90, 105.5, 1000);
+
+            TValue tv = bar;
+
+            Assert.Equal(time, tv.Time);
+            Assert.Equal(105.5, tv.Value);
+        }
+
+        [Fact]
+        public void ToString_WithNaN_DoesNotThrow()
+        {
+            var bar = new TBar(DateTime.UtcNow.Ticks, double.NaN, double.NaN, double.NaN, double.NaN, double.NaN);
+
+            string result = bar.ToString();
+
+            Assert.NotNull(result);
+            Assert.Contains("NaN", result, StringComparison.OrdinalIgnoreCase);
+        }
+
+        [Fact]
+        public void O_H_L_C_V_AllHaveSameTime()
+        {
+            long time = DateTime.UtcNow.Ticks;
+            var bar = new TBar(time, 100, 110, 90, 105, 1000);
+
+            Assert.Equal(time, bar.O.Time);
+            Assert.Equal(time, bar.H.Time);
+            Assert.Equal(time, bar.L.Time);
+            Assert.Equal(time, bar.C.Time);
+            Assert.Equal(time, bar.V.Time);
+        }
+
+        [Fact]
+        public void HLCC4_DoubleWeightsClose()
+        {
+            // HLCC4 = (High + Low + Close + Close) / 4
+            var bar = new TBar(0, 100, 120, 80, 100, 1000);
+
+            // (120 + 80 + 100 + 100) / 4 = 400 / 4 = 100
+            Assert.Equal(100.0, bar.HLCC4);
+        }
+
+        [Fact]
+        public void OHL3_ExcludesClose()
+        {
+            // OHL3 = (Open + High + Low) / 3
+            var bar = new TBar(0, 90, 120, 60, 999, 1000);
+
+            // (90 + 120 + 60) / 3 = 270 / 3 = 90
+            Assert.Equal(90.0, bar.OHL3);
+        }
 }

lib/core/tbarseries/TBarSeries.Tests.cs

@@ -344,7 +344,8 @@ public class TBarSeriesTests
         series.Add(200, 20, 25, 15, 22, 200, isNew: true);
 
         var list = new List<object>();
-
+        
+#pragma warning disable S4158
         foreach (var item in (IEnumerable)series)
         {
                 list.Add(item);
@@ -408,4 +409,146 @@ public class TBarSeriesTests
             Assert.Equal(200, series[1].Time);
         Assert.Equal(300, series[2].Time);
     }
+
+    [Fact]
+    public void Add_WithEnumerables_MismatchedLengths_ThrowsArgumentException()
+    {
+        var series = new TBarSeries();
+        var times = new long[] { 100, 200, 300 };
+        var opens = new double[] { 10, 20 }; // Mismatched length
+        var highs = new double[] { 15, 25, 35 };
+        var lows = new double[] { 5, 15, 25 };
+        var closes = new double[] { 12, 22, 32 };
+        var volumes = new double[] { 100, 200, 300 };
+
+        Assert.Throws<ArgumentException>(() =>
+            series.Add(times, opens, highs, lows, closes, volumes));
+    }
+
+    [Fact]
+    public void Indexer_OutOfBounds_ThrowsException()
+    {
+        var series = new TBarSeries();
+
+        Assert.Throws<ArgumentOutOfRangeException>(() => _ = series[0]);
+    }
+
+    [Fact]
+    public void Indexer_NegativeIndex_ThrowsException()
+    {
+        var series = new TBarSeries();
+        series.Add(100, 10, 15, 5, 12, 100);
+
+        int invalidIndex = -1;
+        Assert.Throws<ArgumentOutOfRangeException>(() => _ = series[invalidIndex]);
+    }
+
+    [Fact]
+    public void Indexer_BeyondCount_ThrowsException()
+    {
+        var series = new TBarSeries();
+        series.Add(100, 10, 15, 5, 12, 100);
+
+        Assert.Throws<ArgumentOutOfRangeException>(() => _ = series[1]);
+    }
+
+    [Fact]
+    public void Add_WithNaN_PreservesNaN()
+    {
+        var series = new TBarSeries();
+        var bar = new TBar(DateTime.UtcNow.Ticks, double.NaN, 110, 90, 105, 1000);
+
+        series.Add(bar, isNew: true);
+
+        Assert.True(double.IsNaN(series.Last.Open));
+        Assert.True(double.IsNaN(series.Open.Last.Value));
+    }
+
+    [Fact]
+    public void Add_WithInfinity_PreservesInfinity()
+    {
+        var series = new TBarSeries();
+        var bar = new TBar(DateTime.UtcNow.Ticks, 100, double.PositiveInfinity, 90, 105, 1000);
+
+        series.Add(bar, isNew: true);
+
+        Assert.True(double.IsPositiveInfinity(series.Last.High));
+        Assert.True(double.IsPositiveInfinity(series.High.Last.Value));
+    }
+
+    [Fact]
+    public void SubSeries_EmptySeries_HaveZeroCount()
+    {
+        var series = new TBarSeries();
+
+        Assert.Empty(series.Open);
+        Assert.Empty(series.High);
+        Assert.Empty(series.Low);
+        Assert.Empty(series.Close);
+        Assert.Empty(series.Volume);
+    }
+
+    [Fact]
+    public void SubSeries_ValuesSpan_ReturnsCorrectData()
+    {
+        var series = new TBarSeries();
+        series.Add(100, 10, 15, 5, 12, 100);
+        series.Add(200, 20, 25, 15, 22, 200);
+
+        ReadOnlySpan<double> closeValues = series.Close.Values;
+
+        Assert.Equal(2, closeValues.Length);
+        Assert.Equal(12.0, closeValues[0]);
+        Assert.Equal(22.0, closeValues[1]);
+    }
+
+    [Fact]
+    public void SubSeries_TimesSpan_ReturnsCorrectData()
+    {
+        var series = new TBarSeries();
+        series.Add(100, 10, 15, 5, 12, 100);
+        series.Add(200, 20, 25, 15, 22, 200);
+
+        ReadOnlySpan<long> times = series.Close.Times;
+
+        Assert.Equal(2, times.Length);
+        Assert.Equal(100, times[0]);
+        Assert.Equal(200, times[1]);
+    }
+
+    [Fact]
+    public void Pub_EventArgs_ContainsIsNewFlag()
+    {
+        var series = new TBarSeries();
+        bool? receivedIsNew = null;
+        series.Pub += (object? sender, in TBarEventArgs args) => receivedIsNew = args.IsNew;
+
+        series.Add(new TBar(100, 10, 15, 5, 12, 100), isNew: true);
+
+        Assert.True(receivedIsNew);
+
+        series.Add(new TBar(100, 10, 18, 5, 15, 150), isNew: false);
+
+        Assert.False(receivedIsNew);
+    }
+
+    [Fact]
+    public void Add_WithEnumerables_EmptyArrays_AddsNothing()
+    {
+        var series = new TBarSeries();
+        var empty = Array.Empty<long>();
+        var emptyD = Array.Empty<double>();
+
+        series.Add(empty, emptyD, emptyD, emptyD, emptyD, emptyD);
+
+        Assert.Empty(series);
+    }
+
+    [Fact]
+    public void Constructor_WithCapacity_DoesNotAffectCount()
+    {
+        var series = new TBarSeries(1000);
+
+        Assert.Empty(series);
+    }
 }

lib/core/tbarseries/tbarseries.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections;
+using System.Collections.Generic;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
@@ -16,6 +17,74 @@ public readonly struct TBarEventArgs
     public bool IsNew { get; init; }
 }
 
+/// <summary>
+/// High-performance enumerator for TBarSeries.
+/// </summary>
+public struct TBarSeriesEnumerator : IEnumerator<TBar>, IEquatable<TBarSeriesEnumerator>
+{
+    private readonly List<long> _t;
+    private readonly List<double> _o;
+    private readonly List<double> _h;
+    private readonly List<double> _l;
+    private readonly List<double> _c;
+    private readonly List<double> _v;
+    private readonly int _count;
+    private int _index;
+    private TBar _current;
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    internal TBarSeriesEnumerator(List<long> t, List<double> o, List<double> h, List<double> l, List<double> c, List<double> v)
+    {
+        _t = t;
+        _o = o;
+        _h = h;
+        _l = l;
+        _c = c;
+        _v = v;
+        _count = c.Count;
+        _index = -1;
+        _current = default;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public bool MoveNext()
+    {
+        if (_index + 1 >= _count)
+            return false;
+
+        _index++;
+        _current = new TBar(_t[_index], _o[_index], _h[_index], _l[_index], _c[_index], _v[_index]);
+        return true;
+    }
+
+    public readonly TBar Current => _current;
+    readonly object IEnumerator.Current => Current;
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public void Reset()
+    {
+        _index = -1;
+        _current = default;
+    }
+
+    public readonly void Dispose() { }
+
+    public readonly bool Equals(TBarSeriesEnumerator other) =>
+        ReferenceEquals(_t, other._t) &&
+        ReferenceEquals(_c, other._c) &&
+        _count == other._count &&
+        _index == other._index;
+
+    public override readonly bool Equals(object? obj) =>
+        obj is TBarSeriesEnumerator other && Equals(other);
+
+    public override readonly int GetHashCode() =>
+        HashCode.Combine(RuntimeHelpers.GetHashCode(_t), RuntimeHelpers.GetHashCode(_c), _count, _index);
+
+    public static bool operator ==(TBarSeriesEnumerator left, TBarSeriesEnumerator right) => left.Equals(right);
+    public static bool operator !=(TBarSeriesEnumerator left, TBarSeriesEnumerator right) => !left.Equals(right);
+}
+
 // Performance-focused event args struct; not derived from EventArgs by design.
 // We intentionally deviate from the standard EventArgs pattern here for perf.
 #pragma warning disable MA0046 // The second parameter must be of type 'System.EventArgs' or a derived type
@@ -94,6 +163,60 @@ public class TBarSeries : IReadOnlyList<TBar>
     public double LastClose { [MethodImpl(MethodImplOptions.AggressiveInlining)] get => _c.Count > 0 ? _c[^1] : double.NaN; }
     public double LastVolume { [MethodImpl(MethodImplOptions.AggressiveInlining)] get => _v.Count > 0 ? _v[^1] : double.NaN; }
 
+    /// <summary>
+    /// Direct access to the underlying Time array as a Span.
+    /// </summary>
+    public ReadOnlySpan<long> Times
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => CollectionsMarshal.AsSpan(_t);
+    }
+
+    /// <summary>
+    /// Direct access to the underlying Open array as a Span for SIMD operations.
+    /// </summary>
+    public ReadOnlySpan<double> OpenValues
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => CollectionsMarshal.AsSpan(_o);
+    }
+
+    /// <summary>
+    /// Direct access to the underlying High array as a Span for SIMD operations.
+    /// </summary>
+    public ReadOnlySpan<double> HighValues
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => CollectionsMarshal.AsSpan(_h);
+    }
+
+    /// <summary>
+    /// Direct access to the underlying Low array as a Span for SIMD operations.
+    /// </summary>
+    public ReadOnlySpan<double> LowValues
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => CollectionsMarshal.AsSpan(_l);
+    }
+
+    /// <summary>
+    /// Direct access to the underlying Close array as a Span for SIMD operations.
+    /// </summary>
+    public ReadOnlySpan<double> CloseValues
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => CollectionsMarshal.AsSpan(_c);
+    }
+
+    /// <summary>
+    /// Direct access to the underlying Volume array as a Span for SIMD operations.
+    /// </summary>
+    public ReadOnlySpan<double> VolumeValues
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => CollectionsMarshal.AsSpan(_v);
+    }
+
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void Add(TBar bar, bool isNew = true)
     {
@@ -150,13 +273,10 @@ public class TBarSeries : IReadOnlyList<TBar>
         }
     }
 
-    public IEnumerator<TBar> GetEnumerator()
-    {
-        for (int i = 0; i < _c.Count; i++)
-        {
-            yield return new TBar(_t[i], _o[i], _h[i], _l[i], _c[i], _v[i]);
-        }
-    }
+    // IEnumerable implementation with struct enumerator for zero-allocation iteration
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public TBarSeriesEnumerator GetEnumerator() => new(_t, _o, _h, _l, _c, _v);
 
+    IEnumerator<TBar> IEnumerable<TBar>.GetEnumerator() => GetEnumerator();
     IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
 }

lib/core/tseries/TSeries.Tests.cs

@@ -285,11 +285,14 @@ public class TSeriesTests
             series.Add(200, 2.0);
 
             var list = new List<object>();
-            foreach (var item in (IEnumerable)series)
+            IEnumerable enumerable = series;
+#pragma warning disable S4158
+        foreach (var item in enumerable)
             {
                 list.Add(item);
             }
 
+            Assert.Equal(2, series.Count);
             Assert.Equal(2, list.Count);
         }
 
@@ -332,4 +335,204 @@ public class TSeriesTests
             series.Add(200, 2.0);
             Assert.Equal(2, series.Count);
     }
+
+    [Fact]
+    public void Constructor_WithMismatchedLists_WrapsData()
+    {
+        // TSeries wraps the lists directly if they're List<T>, no length validation
+        var times = new List<long> { 100, 200, 300 };
+        var values = new List<double> { 1.0, 2.0 }; // Different length
+
+        var series = new TSeries(times, values);
+
+        // Count is based on values list
+        Assert.Equal(2, series.Count);
+    }
+
+    [Fact]
+    public void Indexer_OutOfBounds_ThrowsException()
+    {
+        var series = new TSeries();
+
+        Assert.Throws<ArgumentOutOfRangeException>(() => _ = series[0]);
+    }
+
+    [Fact]
+    public void Indexer_NegativeIndex_ThrowsException()
+    {
+        var series = new TSeries();
+        series.Add(100, 1.0);
+
+#pragma warning disable DS003 // Invalid index - intentional for testing exception
+        Assert.Throws<ArgumentOutOfRangeException>(() => _ = series[-1]);
+#pragma warning restore DS003
+    }
+
+    [Fact]
+    public void Indexer_BeyondCount_ThrowsException()
+    {
+        var series = new TSeries();
+        series.Add(100, 1.0);
+
+        Assert.Throws<ArgumentOutOfRangeException>(() => _ = series[1]);
+    }
+
+    [Fact]
+    public void Values_EmptySeries_ReturnsEmptySpan()
+    {
+        var series = new TSeries();
+
+        ReadOnlySpan<double> values = series.Values;
+
+        Assert.Equal(0, values.Length);
+    }
+
+    [Fact]
+    public void Times_EmptySeries_ReturnsEmptySpan()
+    {
+        var series = new TSeries();
+
+        ReadOnlySpan<long> times = series.Times;
+
+        Assert.Equal(0, times.Length);
+    }
+
+    [Fact]
+    public void Add_WithNaN_PreservesNaN()
+    {
+        var series = new TSeries();
+
+        series.Add(100, double.NaN);
+
+        Assert.True(double.IsNaN(series.Last.Value));
+        Assert.True(double.IsNaN(series.LastValue));
+    }
+
+    [Fact]
+    public void Add_WithInfinity_PreservesInfinity()
+    {
+        var series = new TSeries();
+
+        series.Add(100, double.PositiveInfinity);
+
+        Assert.True(double.IsPositiveInfinity(series.Last.Value));
+        Assert.True(double.IsPositiveInfinity(series.LastValue));
+    }
+
+    [Fact]
+    public void Add_WithNegativeInfinity_PreservesNegativeInfinity()
+    {
+        var series = new TSeries();
+
+        series.Add(100, double.NegativeInfinity);
+
+        Assert.True(double.IsNegativeInfinity(series.Last.Value));
+    }
+
+    [Fact]
+    public void Add_EnumerableDoubles_GeneratesIncreasingTimes()
+    {
+        var series = new TSeries();
+        var values = new[] { 1.0, 2.0, 3.0 };
+
+        series.Add(values);
+
+        Assert.Equal(3, series.Count);
+        // Times should be increasing by TicksPerMinute
+        Assert.True(series[1].Time > series[0].Time);
+        Assert.True(series[2].Time > series[1].Time);
+        Assert.Equal(TimeSpan.TicksPerMinute, series[1].Time - series[0].Time);
+    }
+
+    [Fact]
+    public void Add_EnumerableDoubles_EmptyArray_AddsNothing()
+    {
+        var series = new TSeries();
+
+        series.Add(Array.Empty<double>());
+
+        Assert.Empty(series);
+    }
+
+    [Fact]
+    public void Pub_EventArgs_ContainsIsNewFlag()
+    {
+        var series = new TSeries();
+        bool? receivedIsNew = null;
+        series.Pub += (object? sender, in TValueEventArgs args) => receivedIsNew = args.IsNew;
+
+        series.Add(new TValue(100, 42.0), isNew: true);
+
+        Assert.True(receivedIsNew);
+
+        series.Add(new TValue(100, 43.0), isNew: false);
+
+        Assert.False(receivedIsNew);
+    }
+
+    [Fact]
+    public void Constructor_WithCapacity_DoesNotAffectCount()
+    {
+        var series = new TSeries(1000);
+
+        Assert.Empty(series);
+    }
+
+    [Fact]
+    public void Add_WithDateTimeLocal_ConvertsToUtc()
+    {
+        var series = new TSeries();
+        var localTime = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Local);
+
+        series.Add(localTime, 100.0);
+
+        // The stored time should be UTC
+        var storedTime = new DateTime(series.Last.Time, DateTimeKind.Utc);
+        Assert.Equal(DateTimeKind.Utc, storedTime.Kind);
+    }
+
+    [Fact]
+    public void Add_WithDateTimeUnspecified_TreatsAsLocal()
+    {
+        var series = new TSeries();
+        var unspecifiedTime = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Unspecified);
+
+        series.Add(unspecifiedTime, 100.0);
+
+        Assert.Single(series);
+    }
+
+    [Fact]
+    public void Values_ModifyingUnderlyingList_ReflectsInSpan()
+    {
+        var series = new TSeries();
+        series.Add(100, 1.0);
+        series.Add(200, 2.0);
+
+        // Get the span
+        ReadOnlySpan<double> values1 = series.Values;
+        Assert.Equal(2, values1.Length);
+
+        // Add more data
+        series.Add(300, 3.0);
+
+        // Get new span - should reflect the change
+        ReadOnlySpan<double> values2 = series.Values;
+        Assert.Equal(3, values2.Length);
+        Assert.Equal(3.0, values2[2]);
+    }
+
+    [Fact]
+    public void Constructor_WithReadOnlyLists_CopiesData()
+    {
+        // Using arrays which implement IReadOnlyList but aren't List<T>
+        IReadOnlyList<long> times = new long[] { 100, 200, 300 };
+        IReadOnlyList<double> values = [1.0, 2.0, 3.0];
+
+        var series = new TSeries(times, values);
+
+        Assert.Equal(3, series.Count);
+        Assert.Equal(1.0, series[0].Value);
+        Assert.Equal(3.0, series[2].Value);
+    }
 }

lib/core/tseries/tseries.cs

@@ -6,6 +6,66 @@ using System.Runtime.InteropServices;
 
 namespace QuanTAlib;
 
+/// <summary>
+/// High-performance enumerator for TSeries.
+/// </summary>
+public struct TSeriesEnumerator : IEnumerator<TValue>, IEquatable<TSeriesEnumerator>
+{
+    private readonly List<long> _t;
+    private readonly List<double> _v;
+    private readonly int _count;
+    private int _index;
+    private TValue _current;
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    internal TSeriesEnumerator(List<long> t, List<double> v)
+    {
+        _t = t;
+        _v = v;
+        _count = v.Count;
+        _index = -1;
+        _current = default;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public bool MoveNext()
+    {
+        if (_index + 1 >= _count)
+            return false;
+
+        _index++;
+        _current = new TValue(_t[_index], _v[_index]);
+        return true;
+    }
+
+    public readonly TValue Current => _current;
+    readonly object IEnumerator.Current => Current;
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public void Reset()
+    {
+        _index = -1;
+        _current = default;
+    }
+
+    public readonly void Dispose() { }
+
+    public readonly bool Equals(TSeriesEnumerator other) =>
+        ReferenceEquals(_t, other._t) &&
+        ReferenceEquals(_v, other._v) &&
+        _count == other._count &&
+        _index == other._index;
+
+    public override readonly bool Equals(object? obj) =>
+        obj is TSeriesEnumerator other && Equals(other);
+
+    public override readonly int GetHashCode() =>
+        HashCode.Combine(RuntimeHelpers.GetHashCode(_t), RuntimeHelpers.GetHashCode(_v), _count, _index);
+
+    public static bool operator ==(TSeriesEnumerator left, TSeriesEnumerator right) => left.Equals(right);
+    public static bool operator !=(TSeriesEnumerator left, TSeriesEnumerator right) => !left.Equals(right);
+}
+
 /// <summary>
 /// A high-performance time series implementation using Structure of Arrays (SoA) layout.
 /// Stores Time (long) and Value (double) in separate contiguous arrays for SIMD efficiency.
@@ -132,14 +192,10 @@ public class TSeries : IReadOnlyList<TValue>, ITValuePublisher
         }
     }
 
-    // IEnumerable implementation
-    public IEnumerator<TValue> GetEnumerator()
-    {
-        for (int i = 0; i < _v.Count; i++)
-        {
-            yield return new TValue(_t[i], _v[i]);
-        }
-    }
+    // IEnumerable implementation with struct enumerator for zero-allocation iteration
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public TSeriesEnumerator GetEnumerator() => new(_t, _v);
 
+    IEnumerator<TValue> IEnumerable<TValue>.GetEnumerator() => GetEnumerator();
     IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
 }

lib/core/tvalue/TValue.Tests.cs

@@ -1,182 +1,372 @@
+namespace QuanTAlib.Tests;
 
-namespace QuanTAlib.Tests
+public class TValueTests
 {
-    public class TValueTests
+    [Fact]
+    public void Constructor_WithLongTime_SetsPropertiesCorrectly()
     {
-        [Fact]
-        public void Constructor_WithLongTime_SetsPropertiesCorrectly()
-        {
-            long time = DateTime.UtcNow.Ticks;
-            double value = 123.45;
+        long time = DateTime.UtcNow.Ticks;
+        double value = 123.45;
 
-            var tValue = new TValue(time, value);
+        var tValue = new TValue(time, value);
 
-            Assert.Equal(time, tValue.Time);
-            Assert.Equal(value, tValue.Value);
-        }
+        Assert.Equal(time, tValue.Time);
+        Assert.Equal(value, tValue.Value);
+    }
 
-        [Fact]
-        public void Constructor_WithDateTime_SetsPropertiesCorrectly()
-        {
-            var dateTime = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Utc);
-            double value = 123.45;
+    [Fact]
+    public void Constructor_WithDateTime_SetsPropertiesCorrectly()
+    {
+        var dateTime = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Utc);
+        double value = 123.45;
 
-            var tValue = new TValue(dateTime, value);
+        var tValue = new TValue(dateTime, value);
 
-            Assert.Equal(dateTime.Ticks, tValue.Time);
-            Assert.Equal(value, tValue.Value);
-        }
+        Assert.Equal(dateTime.Ticks, tValue.Time);
+        Assert.Equal(value, tValue.Value);
+    }
 
-        [Fact]
-        public void AsDateTime_ReturnsCorrectDateTime()
-        {
-            var dt = new DateTime(2023, 1, 1, 12, 0, 0, DateTimeKind.Utc);
-            var tValue = new TValue(dt.Ticks, 100.0);
+    [Fact]
+    public void AsDateTime_ReturnsCorrectDateTime()
+    {
+        var dt = new DateTime(2023, 1, 1, 12, 0, 0, DateTimeKind.Utc);
+        var tValue = new TValue(dt.Ticks, 100.0);
 
-            Assert.Equal(dt, tValue.AsDateTime);
-            Assert.Equal(DateTimeKind.Utc, tValue.AsDateTime.Kind);
-        }
+        Assert.Equal(dt, tValue.AsDateTime);
+        Assert.Equal(DateTimeKind.Utc, tValue.AsDateTime.Kind);
+    }
 
-        [Fact]
-        public void ToString_FormatsCorrectly()
-        {
-            var dt = new DateTime(2023, 1, 1, 12, 0, 0, DateTimeKind.Utc);
-            var tValue = new TValue(dt.Ticks, 123.456);
+    [Fact]
+    public void ToString_FormatsCorrectly()
+    {
+        var dt = new DateTime(2023, 1, 1, 12, 0, 0, DateTimeKind.Utc);
+        var tValue = new TValue(dt.Ticks, 123.456);
 
-            string result = tValue.ToString();
+        string result = tValue.ToString();
 
-            Assert.Contains("2023-01-01", result, StringComparison.Ordinal);
-            Assert.Contains("12:00:00", result, StringComparison.Ordinal);
-            Assert.Contains("123.46", result, StringComparison.Ordinal);
-        }
+        Assert.Contains("2023-01-01", result, StringComparison.Ordinal);
+        Assert.Contains("12:00:00", result, StringComparison.Ordinal);
+        Assert.Contains("123.46", result, StringComparison.Ordinal);
+    }
 
-        [Fact]
-        public void ImplicitConversion_ToDouble_ReturnsValue()
-        {
-            var tValue = new TValue(DateTime.UtcNow.Ticks, 42.0);
+    [Fact]
+    public void ImplicitConversion_ToDouble_ReturnsValue()
+    {
+        var tValue = new TValue(DateTime.UtcNow.Ticks, 42.0);
 
-            double val = tValue;
+        double val = tValue;
 
-            Assert.Equal(42.0, val);
-        }
+        Assert.Equal(42.0, val);
+    }
 
-        [Fact]
-        public void ImplicitConversion_ToDateTime_ReturnsCorrectDateTime()
-        {
-            var dateTime = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Utc);
-            var tValue = new TValue(dateTime.Ticks, 100.0);
+    [Fact]
+    public void ImplicitConversion_ToDateTime_ReturnsCorrectDateTime()
+    {
+        var dateTime = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Utc);
+        var tValue = new TValue(dateTime.Ticks, 100.0);
 
-            DateTime result = tValue;
+        DateTime result = tValue;
 
-            Assert.Equal(dateTime, result);
-            Assert.Equal(DateTimeKind.Utc, result.Kind);
-        }
+        Assert.Equal(dateTime, result);
+        Assert.Equal(DateTimeKind.Utc, result.Kind);
+    }
 
-        [Fact]
-        public void Equals_TValue_SameValues_ReturnsTrue()
-        {
-            var tv1 = new TValue(12345, 100.0);
-            var tv2 = new TValue(12345, 100.0);
+    [Fact]
+    public void Equals_TValue_SameValues_ReturnsTrue()
+    {
+        var tv1 = new TValue(12345, 100.0);
+        var tv2 = new TValue(12345, 100.0);
 
-            Assert.True(tv1.Equals(tv2));
-        }
+        Assert.True(tv1.Equals(tv2));
+    }
 
-        [Fact]
-        public void Equals_TValue_DifferentTime_ReturnsFalse()
-        {
-            var tv1 = new TValue(12345, 100.0);
-            var tv2 = new TValue(12346, 100.0);
+    [Fact]
+    public void Equals_TValue_DifferentTime_ReturnsFalse()
+    {
+        var tv1 = new TValue(12345, 100.0);
+        var tv2 = new TValue(12346, 100.0);
 
-            Assert.False(tv1.Equals(tv2));
-        }
+        Assert.False(tv1.Equals(tv2));
+    }
 
-        [Fact]
-        public void Equals_TValue_DifferentValue_ReturnsFalse()
-        {
-            var tv1 = new TValue(12345, 100.0);
-            var tv2 = new TValue(12345, 101.0);
+    [Fact]
+    public void Equals_TValue_DifferentValue_ReturnsFalse()
+    {
+        var tv1 = new TValue(12345, 100.0);
+        var tv2 = new TValue(12345, 101.0);
 
-            Assert.False(tv1.Equals(tv2));
-        }
+        Assert.False(tv1.Equals(tv2));
+    }
 
-        [Fact]
-        public void Equals_Object_SameTValue_ReturnsTrue()
-        {
-            var tv1 = new TValue(12345, 100.0);
-            object tv2 = new TValue(12345, 100.0);
+    [Fact]
+    public void Equals_Object_SameTValue_ReturnsTrue()
+    {
+        var tv1 = new TValue(12345, 100.0);
+        object tv2 = new TValue(12345, 100.0);
 
-            Assert.True(tv1.Equals(tv2));
-        }
+        Assert.True(tv1.Equals(tv2));
+    }
 
-        [Fact]
-        public void Equals_Object_DifferentType_ReturnsFalse()
-        {
-            var tv = new TValue(12345, 100.0);
-            object other = "not a TValue";
+    [Fact]
+    public void Equals_Object_DifferentType_ReturnsFalse()
+    {
+        var tv = new TValue(12345, 100.0);
+        object other = "not a TValue";
 
-            Assert.False(tv.Equals(other));
-        }
+        Assert.False(tv.Equals(other));
+    }
 
-        [Fact]
-        public void Equals_Object_Null_ReturnsFalse()
-        {
-            var tv = new TValue(12345, 100.0);
+    [Fact]
+    public void Equals_Object_Null_ReturnsFalse()
+    {
+        var tv = new TValue(12345, 100.0);
 
-            Assert.False(tv.Equals(null));
-        }
+        Assert.False(tv.Equals(null));
+    }
 
-        [Fact]
-        public void GetHashCode_SameValues_ReturnsSameHashCode()
-        {
-            var tv1 = new TValue(12345, 100.0);
-            var tv2 = new TValue(12345, 100.0);
+    [Fact]
+    public void GetHashCode_SameValues_ReturnsSameHashCode()
+    {
+        var tv1 = new TValue(12345, 100.0);
+        var tv2 = new TValue(12345, 100.0);
 
-            Assert.Equal(tv1.GetHashCode(), tv2.GetHashCode());
-        }
+        Assert.Equal(tv1.GetHashCode(), tv2.GetHashCode());
+    }
 
-        [Fact]
-        public void GetHashCode_DifferentValues_ReturnsDifferentHashCode()
-        {
-            var tv1 = new TValue(12345, 100.0);
-            var tv2 = new TValue(12346, 100.0);
+    [Fact]
+    public void GetHashCode_DifferentValues_ReturnsDifferentHashCode()
+    {
+        var tv1 = new TValue(12345, 100.0);
+        var tv2 = new TValue(12346, 100.0);
 
-            Assert.NotEqual(tv1.GetHashCode(), tv2.GetHashCode());
-        }
+        Assert.NotEqual(tv1.GetHashCode(), tv2.GetHashCode());
+    }
 
-        [Fact]
-        public void EqualityOperator_SameValues_ReturnsTrue()
-        {
-            var tv1 = new TValue(12345, 100.0);
-            var tv2 = new TValue(12345, 100.0);
+    [Fact]
+    public void EqualityOperator_SameValues_ReturnsTrue()
+    {
+        var tv1 = new TValue(12345, 100.0);
+        var tv2 = new TValue(12345, 100.0);
 
-            Assert.True(tv1 == tv2);
-        }
+        Assert.True(tv1 == tv2);
+    }
 
-        [Fact]
-        public void EqualityOperator_DifferentValues_ReturnsFalse()
-        {
-            var tv1 = new TValue(12345, 100.0);
-            var tv2 = new TValue(12346, 100.0);
+    [Fact]
+    public void EqualityOperator_DifferentValues_ReturnsFalse()
+    {
+        var tv1 = new TValue(12345, 100.0);
+        var tv2 = new TValue(12346, 100.0);
 
-            Assert.False(tv1 == tv2);
-        }
+        Assert.False(tv1 == tv2);
+    }
 
-        [Fact]
-        public void InequalityOperator_SameValues_ReturnsFalse()
-        {
-            var tv1 = new TValue(12345, 100.0);
-            var tv2 = new TValue(12345, 100.0);
+    [Fact]
+    public void InequalityOperator_SameValues_ReturnsFalse()
+    {
+        var tv1 = new TValue(12345, 100.0);
+        var tv2 = new TValue(12345, 100.0);
 
-            Assert.False(tv1 != tv2);
-        }
+        Assert.False(tv1 != tv2);
+    }
 
-        [Fact]
-        public void InequalityOperator_DifferentValues_ReturnsTrue()
-        {
-            var tv1 = new TValue(12345, 100.0);
-            var tv2 = new TValue(12346, 100.0);
+    [Fact]
+    public void InequalityOperator_DifferentValues_ReturnsTrue()
+    {
+        var tv1 = new TValue(12345, 100.0);
+        var tv2 = new TValue(12346, 100.0);
 
-            Assert.True(tv1 != tv2);
-        }
+        Assert.True(tv1 != tv2);
+    }
+
+    [Fact]
+    public void Constructor_WithDateTimeLocal_ConvertsToUtc()
+    {
+        var localTime = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Local);
+        double value = 123.45;
+
+        var tValue = new TValue(localTime, value);
+
+        // Time should be stored as UTC ticks
+        var expectedUtc = localTime.ToUniversalTime();
+        Assert.Equal(expectedUtc.Ticks, tValue.Time);
+    }
+
+    [Fact]
+    public void Constructor_WithDateTimeUnspecified_ConvertsToUtc()
+    {
+        var unspecifiedTime = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Unspecified);
+        double value = 123.45;
+
+        var tValue = new TValue(unspecifiedTime, value);
+
+        // Unspecified is treated as local and converted to UTC
+        var expectedUtc = unspecifiedTime.ToUniversalTime();
+        Assert.Equal(expectedUtc.Ticks, tValue.Time);
+    }
+
+    [Fact]
+    public void Constructor_WithDateTimeUtc_PreservesTicks()
+    {
+        var utcTime = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Utc);
+        double value = 123.45;
+
+        var tValue = new TValue(utcTime, value);
+
+        Assert.Equal(utcTime.Ticks, tValue.Time);
+    }
+
+    [Fact]
+    public void Default_TValue_HasZeroTimeAndValue()
+    {
+        var defaultTValue = default(TValue);
+
+        Assert.Equal(0, defaultTValue.Time);
+        Assert.Equal(0.0, defaultTValue.Value);
+    }
+
+    [Fact]
+    public void Constructor_WithNaN_PreservesNaN()
+    {
+        var tValue = new TValue(DateTime.UtcNow.Ticks, double.NaN);
+
+        Assert.True(double.IsNaN(tValue.Value));
+    }
+
+    [Fact]
+    public void Constructor_WithPositiveInfinity_PreservesInfinity()
+    {
+        var tValue = new TValue(DateTime.UtcNow.Ticks, double.PositiveInfinity);
+
+        Assert.True(double.IsPositiveInfinity(tValue.Value));
+    }
+
+    [Fact]
+    public void Constructor_WithNegativeInfinity_PreservesInfinity()
+    {
+        var tValue = new TValue(DateTime.UtcNow.Ticks, double.NegativeInfinity);
+
+        Assert.True(double.IsNegativeInfinity(tValue.Value));
+    }
+
+    [Fact]
+    public void Constructor_WithMaxValue_PreservesMaxValue()
+    {
+        var tValue = new TValue(DateTime.UtcNow.Ticks, double.MaxValue);
+
+        Assert.Equal(double.MaxValue, tValue.Value);
+    }
+
+    [Fact]
+    public void Constructor_WithMinValue_PreservesMinValue()
+    {
+        var tValue = new TValue(DateTime.UtcNow.Ticks, double.MinValue);
+
+        Assert.Equal(double.MinValue, tValue.Value);
+    }
+
+    [Fact]
+    public void Constructor_WithEpsilon_PreservesEpsilon()
+    {
+        var tValue = new TValue(DateTime.UtcNow.Ticks, double.Epsilon);
+
+        Assert.Equal(double.Epsilon, tValue.Value);
+    }
+
+    [Fact]
+    public void ImplicitConversion_ToDouble_WithNaN_ReturnsNaN()
+    {
+        var tValue = new TValue(DateTime.UtcNow.Ticks, double.NaN);
+
+        double val = tValue;
+
+        Assert.True(double.IsNaN(val));
+    }
+
+    [Fact]
+    public void ToString_WithNaN_FormatsCorrectly()
+    {
+        var dt = new DateTime(2023, 1, 1, 12, 0, 0, DateTimeKind.Utc);
+        var tValue = new TValue(dt.Ticks, double.NaN);
+
+        string result = tValue.ToString();
+
+        Assert.Contains("NaN", result, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void ToString_WithInfinity_FormatsCorrectly()
+    {
+        var dt = new DateTime(2023, 1, 1, 12, 0, 0, DateTimeKind.Utc);
+        var tValue = new TValue(dt.Ticks, double.PositiveInfinity);
+
+        string result = tValue.ToString();
+
+        Assert.Contains("∞", result, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void ToString_WithNegativeValue_FormatsCorrectly()
+    {
+        var dt = new DateTime(2023, 1, 1, 12, 0, 0, DateTimeKind.Utc);
+        var tValue = new TValue(dt.Ticks, -123.456);
+
+        string result = tValue.ToString();
+
+        Assert.Contains("-123.46", result, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void AsDateTime_ReturnsUtcKind()
+    {
+        var tValue = new TValue(DateTime.UtcNow.Ticks, 100.0);
+
+        Assert.Equal(DateTimeKind.Utc, tValue.AsDateTime.Kind);
+    }
+
+    [Fact]
+    public void Equals_WithNaN_BothNaN_ReturnsFalse()
+    {
+        // NaN != NaN in IEEE 754
+        var tv1 = new TValue(12345, double.NaN);
+        var tv2 = new TValue(12345, double.NaN);
+
+        // Record struct equality compares fields directly
+        // double.NaN.Equals(double.NaN) returns true in .NET
+        Assert.True(tv1.Equals(tv2));
+    }
+
+    [Fact]
+    public void GetHashCode_WithNaN_DoesNotThrow()
+    {
+        var tv = new TValue(12345, double.NaN);
+
+        var hash = tv.GetHashCode();
+
+        Assert.True(hash != 0 || hash == 0); // Just verify it doesn't throw
+    }
+
+    [Fact]
+    public void Constructor_WithZeroTime_Allowed()
+    {
+        var tValue = new TValue(0, 100.0);
+
+        Assert.Equal(0, tValue.Time);
+        Assert.Equal(100.0, tValue.Value);
+    }
+
+    [Fact]
+    public void Constructor_WithNegativeTime_Allowed()
+    {
+        var tValue = new TValue(-12345, 100.0);
+
+        Assert.Equal(-12345, tValue.Time);
+    }
+
+    [Fact]
+    public void Constructor_WithMaxLongTime_Allowed()
+    {
+        var tValue = new TValue(long.MaxValue, 100.0);
+
+        Assert.Equal(long.MaxValue, tValue.Time);
     }
 }

lib/feeds/csv/CsvFeed.Tests.cs

@@ -1,15 +1,42 @@
 
 namespace QuanTAlib.Tests;
 
-public class CsvFeedTests
+public sealed class CsvFeedTests : IDisposable
 {
     private const string TestCsvPath = "daily_IBM.csv";
+    private readonly List<string> _tempFiles = new();
+    private bool _disposed;
+
+    public void Dispose()
+    {
+        if (_disposed) return;
+        _disposed = true;
+
+        foreach (var file in _tempFiles)
+        {
+            if (File.Exists(file))
+            {
+                try { File.Delete(file); } catch { /* ignore */ }
+            }
+        }
+    }
+
+    private string CreateTempCsv(string[] lines)
+    {
+        string tempPath = Path.GetTempFileName() + ".csv";
+        File.WriteAllLines(tempPath, lines);
+        _tempFiles.Add(tempPath);
+        return tempPath;
+    }
+
+    #region Constructor Tests
 
     [Fact]
     public void Constructor_ValidFile_LoadsData()
     {
         var feed = new CsvFeed(TestCsvPath);
         Assert.NotNull(feed);
+        Assert.True(feed.Count > 0);
     }
 
     [Fact]
@@ -21,15 +48,185 @@ public class CsvFeedTests
     [Fact]
     public void Constructor_NullPath_ThrowsArgumentException()
     {
-        Assert.Throws<ArgumentException>(() => new CsvFeed(null!));
+        var ex = Assert.Throws<ArgumentException>(() => new CsvFeed(null!));
+        Assert.Equal("filePath", ex.ParamName);
     }
 
     [Fact]
     public void Constructor_EmptyPath_ThrowsArgumentException()
     {
-        Assert.Throws<ArgumentException>(() => new CsvFeed(""));
+        var ex = Assert.Throws<ArgumentException>(() => new CsvFeed(""));
+        Assert.Equal("filePath", ex.ParamName);
     }
 
+    [Fact]
+    public void Constructor_WhitespacePath_ThrowsArgumentException()
+    {
+        var ex = Assert.Throws<ArgumentException>(() => new CsvFeed("   "));
+        Assert.Equal("filePath", ex.ParamName);
+    }
+
+    [Fact]
+    public void Constructor_EmptyCsv_ThrowsInvalidDataException()
+    {
+        string tempCsv = CreateTempCsv(Array.Empty<string>());
+        Assert.Throws<InvalidDataException>(() => new CsvFeed(tempCsv));
+    }
+
+    [Fact]
+    public void Constructor_HeaderOnlyCsv_ThrowsInvalidDataException()
+    {
+        string tempCsv = CreateTempCsv(new[] { "timestamp,open,high,low,close,volume" });
+        Assert.Throws<InvalidDataException>(() => new CsvFeed(tempCsv));
+    }
+
+    [Fact]
+    public void Constructor_MalformedDate_ThrowsFormatException()
+    {
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "not-a-date,100,101,99,100,1000"
+        });
+        Assert.Throws<FormatException>(() => new CsvFeed(tempCsv));
+    }
+
+    [Fact]
+    public void Constructor_MalformedPrice_ThrowsFormatException()
+    {
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "2023-01-01,not-a-number,101,99,100,1000"
+        });
+        Assert.Throws<FormatException>(() => new CsvFeed(tempCsv));
+    }
+
+    [Fact]
+    public void Constructor_MissingColumns_ThrowsFormatException()
+    {
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "2023-01-01,100,101,99,100"  // Missing volume
+        });
+        Assert.Throws<FormatException>(() => new CsvFeed(tempCsv));
+    }
+
+    [Fact]
+    public void Constructor_ExtraColumns_ThrowsFormatException()
+    {
+        // Extra columns should throw format exception (strict 6-column format)
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume,extra",
+            "2023-01-01,100,101,99,100,1000,extra_data"
+        });
+        Assert.Throws<FormatException>(() => new CsvFeed(tempCsv));
+    }
+
+    #endregion
+
+    #region Property Tests
+
+    [Fact]
+    public void Count_ReturnsCorrectNumber()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        Assert.True(feed.Count > 0);
+        // IBM CSV has 100 rows of data
+        Assert.Equal(100, feed.Count);
+    }
+
+    [Fact]
+    public void FilePath_ReturnsLoadedPath()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        Assert.Equal(TestCsvPath, feed.FilePath);
+    }
+
+    [Fact]
+    public void HasMore_TrueAtStart()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        Assert.True(feed.HasMore);
+    }
+
+    [Fact]
+    public void HasMore_FalseWhenExhausted()
+    {
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "2023-01-01,100,101,99,100,1000"
+        });
+        var feed = new CsvFeed(tempCsv);
+
+        Assert.True(feed.HasMore);
+        feed.Next(isNew: true);
+        Assert.False(feed.HasMore);
+    }
+
+    [Fact]
+    public void CurrentIndex_StartsAtZero()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        Assert.Equal(0, feed.CurrentIndex);
+    }
+
+    [Fact]
+    public void CurrentIndex_IncrementsOnNext()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        Assert.Equal(0, feed.CurrentIndex);
+        feed.Next(isNew: true);
+        Assert.Equal(1, feed.CurrentIndex);
+        feed.Next(isNew: true);
+        Assert.Equal(2, feed.CurrentIndex);
+    }
+
+    [Fact]
+    public void CurrentIndex_DoesNotIncrementOnUpdate()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        feed.Next(isNew: true);
+        int indexAfterFirst = feed.CurrentIndex;
+
+        feed.Next(isNew: false);
+        Assert.Equal(indexAfterFirst, feed.CurrentIndex);
+    }
+
+    [Fact]
+    public void HasCurrentBar_FalseAtStart()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        Assert.False(feed.HasCurrentBar);
+    }
+
+    [Fact]
+    public void HasCurrentBar_TrueAfterNext()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        feed.Next(isNew: true);
+        Assert.True(feed.HasCurrentBar);
+    }
+
+    [Fact]
+    public void Data_ReturnsUnderlyingSeries()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        var data = feed.Data;
+
+        Assert.NotNull(data);
+        Assert.Equal(feed.Count, data.Count);
+    }
+
+    #endregion
+
+    #region Next Method Tests
+
     [Fact]
     public void Next_StreamsDataChronologically()
     {
@@ -109,6 +306,43 @@ public class CsvFeedTests
         Assert.Equal(lastBar.Time, finalBar.Time);
     }
 
+    [Fact]
+    public void Next_EmptyData_ReturnsDefaultAndSignalsNoMore()
+    {
+        // Create a mock scenario - but since constructor throws on empty,
+        // we test the behavior when all data is consumed
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "2023-01-01,100,101,99,100,1000"
+        });
+        var feed = new CsvFeed(tempCsv);
+
+        // Consume all data
+        bool isNew = true;
+        feed.Next(ref isNew);
+
+        // Now at end
+        isNew = true;
+        var bar = feed.Next(ref isNew);
+        Assert.False(isNew);
+        Assert.Equal(100.0, bar.Close); // Returns last bar
+    }
+
+    [Fact]
+    public void Next_DefaultParameter_IsNewTrue()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        var bar1 = feed.Next(); // Default isNew = true
+        var bar2 = feed.Next(); // Default isNew = true
+        Assert.True(bar2.Time > bar1.Time);
+    }
+
+    #endregion
+
+    #region Fetch Method Tests
+
     [Fact]
     public void Fetch_ReturnsCorrectNumberOfBars()
     {
@@ -124,15 +358,25 @@ public class CsvFeedTests
     }
 
     [Fact]
-    public void Fetch_InvalidCount_ThrowsArgumentException()
+    public void Fetch_ZeroCount_ThrowsArgumentException()
     {
         var feed = new CsvFeed(TestCsvPath);
-
         var startTime = DateTime.UtcNow.Ticks;
         var interval = TimeSpan.FromDays(1);
 
-        Assert.Throws<ArgumentException>(() => feed.Fetch(0, startTime, interval));
-        Assert.Throws<ArgumentException>(() => feed.Fetch(-1, startTime, interval));
+        var ex = Assert.Throws<ArgumentException>(() => feed.Fetch(0, startTime, interval));
+        Assert.Equal("count", ex.ParamName);
+    }
+
+    [Fact]
+    public void Fetch_NegativeCount_ThrowsArgumentException()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        var startTime = DateTime.UtcNow.Ticks;
+        var interval = TimeSpan.FromDays(1);
+
+        var ex = Assert.Throws<ArgumentException>(() => feed.Fetch(-1, startTime, interval));
+        Assert.Equal("count", ex.ParamName);
     }
 
     [Fact]
@@ -154,6 +398,174 @@ public class CsvFeedTests
         Assert.True(bar.Time >= startTime);
     }
 
+    [Fact]
+    public void Fetch_ResetsHasCurrentBar()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        feed.Next(isNew: true);
+        Assert.True(feed.HasCurrentBar);
+
+        var startTime = new DateTime(2025, 7, 1, 0, 0, 0, DateTimeKind.Utc).Ticks;
+        feed.Fetch(5, startTime, TimeSpan.FromDays(1));
+
+        Assert.False(feed.HasCurrentBar);
+    }
+
+    #endregion
+
+    #region Reset Method Tests
+
+    [Fact]
+    public void Reset_ReturnsToStart()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        // Advance several bars
+        var firstBar = feed.Next(isNew: true);
+        feed.Next(isNew: true);
+        feed.Next(isNew: true);
+        Assert.Equal(3, feed.CurrentIndex);
+
+        // Reset
+        feed.Reset();
+
+        Assert.Equal(0, feed.CurrentIndex);
+        Assert.True(feed.HasMore);
+        Assert.False(feed.HasCurrentBar);
+
+        // Next bar should be first bar again
+        var afterReset = feed.Next(isNew: true);
+        Assert.Equal(firstBar.Time, afterReset.Time);
+        Assert.Equal(firstBar.Close, afterReset.Close);
+    }
+
+    [Fact]
+    public void Reset_WithIndex_SetsCorrectPosition()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        // Reset to middle
+        int targetIndex = 50;
+        feed.Reset(targetIndex);
+
+        Assert.Equal(targetIndex, feed.CurrentIndex);
+        Assert.False(feed.HasCurrentBar);
+
+        // Next bar should be at that index
+        var bar = feed.Next(isNew: true);
+        var expectedBar = feed.GetBar(targetIndex);
+        Assert.Equal(expectedBar.Time, bar.Time);
+    }
+
+    [Fact]
+    public void Reset_WithNegativeIndex_ThrowsArgumentOutOfRangeException()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        var ex = Assert.Throws<ArgumentOutOfRangeException>(() => feed.Reset(-1));
+        Assert.Equal("index", ex.ParamName);
+    }
+
+    [Fact]
+    public void Reset_WithIndexBeyondCount_ThrowsArgumentOutOfRangeException()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        var ex = Assert.Throws<ArgumentOutOfRangeException>(() => feed.Reset(feed.Count + 1));
+        Assert.Equal("index", ex.ParamName);
+    }
+
+    [Fact]
+    public void Reset_WithIndexAtCount_IsValid()
+    {
+        // Resetting to exactly Count means "at end" - valid but no more data
+        var feed = new CsvFeed(TestCsvPath);
+        feed.Reset(feed.Count);
+
+        Assert.Equal(feed.Count, feed.CurrentIndex);
+        Assert.False(feed.HasMore);
+    }
+
+    #endregion
+
+    #region GetBar Method Tests
+
+    [Fact]
+    public void GetBar_ReturnsCorrectBar()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        // Get bar without affecting streaming
+        var bar0 = feed.GetBar(0);
+        var bar1 = feed.GetBar(1);
+
+        // Streaming position unchanged
+        Assert.Equal(0, feed.CurrentIndex);
+
+        // Bars should be in chronological order
+        Assert.True(bar1.Time > bar0.Time);
+    }
+
+    [Fact]
+    public void GetBar_NegativeIndex_ThrowsArgumentOutOfRangeException()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        var ex = Assert.Throws<ArgumentOutOfRangeException>(() => feed.GetBar(-1));
+        Assert.Equal("index", ex.ParamName);
+    }
+
+    [Fact]
+    public void GetBar_IndexAtCount_ThrowsArgumentOutOfRangeException()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+        var ex = Assert.Throws<ArgumentOutOfRangeException>(() => feed.GetBar(feed.Count));
+        Assert.Equal("index", ex.ParamName);
+    }
+
+    [Fact]
+    public void GetBar_DoesNotAffectStreaming()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        // Stream first bar
+        var streamed = feed.Next(isNew: true);
+        int indexAfter = feed.CurrentIndex;
+
+        // Random access
+        var bar50 = feed.GetBar(50);
+        Assert.True(bar50.Time > 0);
+
+        // Streaming position unchanged
+        Assert.Equal(indexAfter, feed.CurrentIndex);
+
+        // Continue streaming
+        var next = feed.Next(isNew: true);
+        Assert.True(next.Time > streamed.Time);
+    }
+
+    [Fact]
+    public void GetBar_ConsistentWithNext()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        // Get bars via random access
+        var bar0 = feed.GetBar(0);
+        var bar1 = feed.GetBar(1);
+        var bar2 = feed.GetBar(2);
+
+        // Get same bars via streaming
+        var streamed0 = feed.Next(isNew: true);
+        var streamed1 = feed.Next(isNew: true);
+        var streamed2 = feed.Next(isNew: true);
+
+        Assert.Equal(bar0.Time, streamed0.Time);
+        Assert.Equal(bar1.Time, streamed1.Time);
+        Assert.Equal(bar2.Time, streamed2.Time);
+    }
+
+    #endregion
+
+    #region OHLCV Validation Tests
+
     [Fact]
     public void LoadFromCsv_ParsesValuesCorrectly()
     {
@@ -190,10 +602,91 @@ public class CsvFeedTests
         for (int i = 1; i < bars.Count; i++)
         {
             Assert.True(bars[i].Time > bars[i - 1].Time,
-                $"Bar {i} time ({bars[i].AsDateTime}) should be after bar {i-1} time ({bars[i-1].AsDateTime})");
+                $"Bar {i} time ({bars[i].AsDateTime}) should be after bar {i - 1} time ({bars[i - 1].AsDateTime})");
         }
     }
 
+    [Fact]
+    public void LoadFromCsv_AllBarsHaveValidOHLCV()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        for (int i = 0; i < feed.Count; i++)
+        {
+            var bar = feed.GetBar(i);
+
+            Assert.True(double.IsFinite(bar.Open), $"Bar {i} has non-finite Open");
+            Assert.True(double.IsFinite(bar.High), $"Bar {i} has non-finite High");
+            Assert.True(double.IsFinite(bar.Low), $"Bar {i} has non-finite Low");
+            Assert.True(double.IsFinite(bar.Close), $"Bar {i} has non-finite Close");
+            Assert.True(double.IsFinite(bar.Volume), $"Bar {i} has non-finite Volume");
+
+            Assert.True(bar.High >= bar.Low, $"Bar {i}: High ({bar.High}) < Low ({bar.Low})");
+            Assert.True(bar.High >= bar.Open, $"Bar {i}: High ({bar.High}) < Open ({bar.Open})");
+            Assert.True(bar.High >= bar.Close, $"Bar {i}: High ({bar.High}) < Close ({bar.Close})");
+            Assert.True(bar.Low <= bar.Open, $"Bar {i}: Low ({bar.Low}) > Open ({bar.Open})");
+            Assert.True(bar.Low <= bar.Close, $"Bar {i}: Low ({bar.Low}) > Close ({bar.Close})");
+        }
+    }
+
+    [Fact]
+    public void LoadFromCsv_ParsesDecimalsCorrectly()
+    {
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "2023-01-01,100.1234,101.5678,99.9999,100.0001,1234567.89"
+        });
+        var feed = new CsvFeed(tempCsv);
+        var bar = feed.Next(isNew: true);
+
+        Assert.Equal(100.1234, bar.Open, precision: 4);
+        Assert.Equal(101.5678, bar.High, precision: 4);
+        Assert.Equal(99.9999, bar.Low, precision: 4);
+        Assert.Equal(100.0001, bar.Close, precision: 4);
+        Assert.Equal(1234567.89, bar.Volume, precision: 2);
+    }
+
+    [Fact]
+    public void LoadFromCsv_ParsesNegativeValues()
+    {
+        // While negative prices are unusual, the parser should handle them
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "2023-01-01,-100,50,-150,-50,1000"
+        });
+        var feed = new CsvFeed(tempCsv);
+        var bar = feed.Next(isNew: true);
+
+        Assert.Equal(-100, bar.Open);
+        Assert.Equal(50, bar.High);
+        Assert.Equal(-150, bar.Low);
+        Assert.Equal(-50, bar.Close);
+    }
+
+    [Fact]
+    public void LoadFromCsv_ParsesScientificNotation()
+    {
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "2023-01-01,1.5e2,2e2,1e2,1.75e2,1e6"
+        });
+        var feed = new CsvFeed(tempCsv);
+        var bar = feed.Next(isNew: true);
+
+        Assert.Equal(150, bar.Open);
+        Assert.Equal(200, bar.High);
+        Assert.Equal(100, bar.Low);
+        Assert.Equal(175, bar.Close);
+        Assert.Equal(1000000, bar.Volume);
+    }
+
+    #endregion
+
+    #region IFeed Interface Tests
+
     [Fact]
     public void CsvFeed_WorksWithIFeedInterface()
     {
@@ -206,6 +699,35 @@ public class CsvFeedTests
         Assert.True(bar2.Time > bar1.Time);
     }
 
+    [Fact]
+    public void CsvFeed_IFeedRefOverload()
+    {
+        IFeed feed = new CsvFeed(TestCsvPath);
+
+        bool isNew = true;
+        var bar1 = feed.Next(ref isNew);
+        Assert.True(bar1.Time > 0);
+
+        isNew = false;
+        var bar1Update = feed.Next(ref isNew);
+        Assert.Equal(bar1.Time, bar1Update.Time);
+    }
+
+    [Fact]
+    public void CsvFeed_IFeedFetch()
+    {
+        IFeed feed = new CsvFeed(TestCsvPath);
+
+        var startTime = new DateTime(2025, 7, 1, 0, 0, 0, DateTimeKind.Utc).Ticks;
+        var series = feed.Fetch(5, startTime, TimeSpan.FromDays(1));
+
+        Assert.True(series.Count > 0);
+    }
+
+    #endregion
+
+    #region Edge Case Tests
+
     [Fact]
     public void Next_MixedNewAndUpdate_WorksCorrectly()
     {
@@ -248,49 +770,160 @@ public class CsvFeedTests
         var series = feed.Fetch(5, startTime, TimeSpan.FromDays(1));
 
         // Should return empty or minimal data
-        Assert.True(series.Count == 0);
+        Assert.Empty(series);
     }
 
     [Fact]
     public void Fetch_HandlesGapsCorrectly()
     {
-        string tempCsv = Path.GetTempFileName() + ".csv";
-        try
+        // Create CSV with gaps using helper
+        string tempCsv = CreateTempCsv(new[]
         {
-            // Create CSV with gaps
-            // Date, Open, High, Low, Close, Volume
-            // 2023-01-01 (Sunday)
-            // 2023-01-02 (Monday)
-            // 2023-01-04 (Wednesday) - Gap of Tuesday
-            // 2023-01-05 (Thursday)
-            var lines = new[]
-            {
-                "Date,Open,High,Low,Close,Volume",
-                "2023-01-05,103,104,102,103,1000",
-                "2023-01-04,102,103,101,102,1000",
-                "2023-01-02,101,102,100,101,1000",
-                "2023-01-01,100,101,99,100,1000"
-            };
-            File.WriteAllLines(tempCsv, lines);
+            "timestamp,open,high,low,close,volume",
+            "2023-01-05,103,104,102,103,1000",
+            "2023-01-04,102,103,101,102,1000",
+            "2023-01-02,101,102,100,101,1000",
+            "2023-01-01,100,101,99,100,1000"
+        });
 
-            var feed = new CsvFeed(tempCsv);
-            var startTime = new DateTime(2023, 1, 1, 0, 0, 0, DateTimeKind.Utc).Ticks;
-            var interval = TimeSpan.FromDays(1);
+        var feed = new CsvFeed(tempCsv);
+        var startTime = new DateTime(2023, 1, 1, 0, 0, 0, DateTimeKind.Utc).Ticks;
+        var interval = TimeSpan.FromDays(1);
 
-            // Fetch 5 bars. Should get 4 bars (Jan 1, 2, 4, 5).
-            var series = feed.Fetch(10, startTime, interval);
+        // Fetch bars. Should get 4 bars (Jan 1, 2, 4, 5).
+        var series = feed.Fetch(10, startTime, interval);
 
-            Assert.Equal(4, series.Count);
-            Assert.Equal(startTime, series[0].Time); // Jan 1
-            Assert.Equal(startTime + interval.Ticks, series[1].Time); // Jan 2
-            // Gap here
-            Assert.Equal(startTime + 3 * interval.Ticks, series[2].Time); // Jan 4
-            Assert.Equal(startTime + 4 * interval.Ticks, series[3].Time); // Jan 5
+        Assert.Equal(4, series.Count);
+        Assert.Equal(startTime, series[0].Time); // Jan 1
+        Assert.Equal(startTime + interval.Ticks, series[1].Time); // Jan 2
+        // Gap here (Jan 3 missing)
+        Assert.Equal(startTime + 3 * interval.Ticks, series[2].Time); // Jan 4
+        Assert.Equal(startTime + 4 * interval.Ticks, series[3].Time); // Jan 5
+    }
+
+    [Fact]
+    public void SingleBar_StreamsAndEnds()
+    {
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "2023-01-01,100,101,99,100,1000"
+        });
+        var feed = new CsvFeed(tempCsv);
+
+        Assert.Equal(1, feed.Count);
+        Assert.True(feed.HasMore);
+
+        bool isNew = true;
+        var bar = feed.Next(ref isNew);
+        Assert.True(isNew);
+        Assert.Equal(100.0, bar.Close);
+        Assert.False(feed.HasMore);
+
+        // Try to get next
+        isNew = true;
+        var noMore = feed.Next(ref isNew);
+        Assert.False(isNew); // Signals end
+        Assert.Equal(bar.Time, noMore.Time); // Returns last bar
+    }
+
+    [Fact]
+    public void WhitespaceInValues_Trimmed()
+    {
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "  2023-01-01  ,  100  ,  101  ,  99  ,  100  ,  1000  "
+        });
+        var feed = new CsvFeed(tempCsv);
+        var bar = feed.Next(isNew: true);
+
+        Assert.Equal(100.0, bar.Open);
+        Assert.Equal(101.0, bar.High);
+        Assert.Equal(99.0, bar.Low);
+        Assert.Equal(100.0, bar.Close);
+        Assert.Equal(1000.0, bar.Volume);
+    }
+
+    [Fact]
+    public void ZeroValues_Accepted()
+    {
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "2023-01-01,0,0,0,0,0"
+        });
+        var feed = new CsvFeed(tempCsv);
+        var bar = feed.Next(isNew: true);
+
+        Assert.Equal(0.0, bar.Open);
+        Assert.Equal(0.0, bar.High);
+        Assert.Equal(0.0, bar.Low);
+        Assert.Equal(0.0, bar.Close);
+        Assert.Equal(0.0, bar.Volume);
+    }
+
+    [Fact]
+    public void VeryLargeValues_Parsed()
+    {
+        string tempCsv = CreateTempCsv(new[]
+        {
+            "timestamp,open,high,low,close,volume",
+            "2023-01-01,999999999.99,1000000000.01,999999999.00,999999999.50,9999999999999"
+        });
+        var feed = new CsvFeed(tempCsv);
+        var bar = feed.Next(isNew: true);
+
+        Assert.Equal(999999999.99, bar.Open, precision: 2);
+        Assert.Equal(1000000000.01, bar.High, precision: 2);
+        Assert.Equal(999999999.00, bar.Low, precision: 2);
+        Assert.Equal(999999999.50, bar.Close, precision: 2);
+        Assert.Equal(9999999999999.0, bar.Volume, precision: 0);
+    }
+
+    [Fact]
+    public void ConsecutiveResets_WorkCorrectly()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        feed.Next(isNew: true);
+        feed.Next(isNew: true);
+        feed.Reset();
+        feed.Reset();
+        feed.Reset();
+
+        Assert.Equal(0, feed.CurrentIndex);
+        Assert.False(feed.HasCurrentBar);
+    }
+
+    [Fact]
+    public void StreamThenResetThenStream_Consistent()
+    {
+        var feed = new CsvFeed(TestCsvPath);
+
+        // First pass
+        var firstPass = new List<double>();
+        for (int i = 0; i < 10; i++)
+        {
+            firstPass.Add(feed.Next(isNew: true).Close);
         }
-        finally
+
+        // Reset
+        feed.Reset();
+
+        // Second pass
+        var secondPass = new List<double>();
+        for (int i = 0; i < 10; i++)
         {
-            if (File.Exists(tempCsv))
-                File.Delete(tempCsv);
+            secondPass.Add(feed.Next(isNew: true).Close);
+        }
+
+        // Should be identical
+        for (int i = 0; i < 10; i++)
+        {
+            Assert.Equal(firstPass[i], secondPass[i]);
         }
     }
+
+    #endregion
 }

lib/feeds/csv/CsvFeed.cs

@@ -1,28 +1,80 @@
 using System.Globalization;
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 
 namespace QuanTAlib;
 
+/// <summary>
+/// Parsed OHLCV data from a CSV line.
+/// </summary>
+[StructLayout(LayoutKind.Auto)]
+internal readonly record struct ParsedOhlcv(long Time, double Open, double High, double Low, double Close, double Volume);
+
+/// <summary>
+/// Mutable state for parsing OHLCV columns. Used as ref parameter to reduce method signature size.
+/// </summary>
+[StructLayout(LayoutKind.Auto)]
+internal ref struct OhlcvParseState
+{
+    public long Time;
+    public double Open;
+    public double High;
+    public double Low;
+    public double Close;
+    public double Volume;
+}
+
 /// <summary>
 /// CSV file feed for loading historical OHLCV data.
 /// Loads data in constructor and streams through it with Next() or returns batches with Fetch().
 /// CSV format: timestamp,open,high,low,close,volume (header required)
 /// Timestamp format: YYYY-MM-DD (UTC midnight assumed)
 /// </summary>
-public class CsvFeed : IFeed
+[SkipLocalsInit]
+public sealed class CsvFeed : IFeed
 {
     private readonly TBarSeries _data;
+    private readonly string _filePath;
 
     // Streaming state
     private int _currentIndex;
     private TBar _currentBar;
     private bool _hasCurrentBar;
 
+    /// <summary>
+    /// Gets the total number of bars available in the CSV file.
+    /// </summary>
+    public int Count => _data.Count;
+
+    /// <summary>
+    /// Gets the file path of the loaded CSV.
+    /// </summary>
+    public string FilePath => _filePath;
+
+    /// <summary>
+    /// Gets whether there are more bars to stream.
+    /// </summary>
+    public bool HasMore => _currentIndex < _data.Count;
+
+    /// <summary>
+    /// Gets the current streaming position (0-based index).
+    /// </summary>
+    public int CurrentIndex => _currentIndex;
+
+    /// <summary>
+    /// Gets whether the feed has a current bar in progress.
+    /// </summary>
+    public bool HasCurrentBar => _hasCurrentBar;
+
     /// <summary>
     /// Loads CSV file and prepares data for streaming.
     /// Data is reversed to chronological order (oldest first).
     /// </summary>
     /// <param name="filePath">Path to CSV file</param>
+    /// <exception cref="ArgumentException">Thrown when filePath is null or empty</exception>
+    /// <exception cref="FileNotFoundException">Thrown when the specified file does not exist</exception>
+    /// <exception cref="InvalidDataException">Thrown when CSV file is empty or contains only header</exception>
+    /// <exception cref="FormatException">Thrown when CSV format is invalid</exception>
     public CsvFeed(string filePath)
     {
         if (string.IsNullOrWhiteSpace(filePath))
@@ -31,6 +83,7 @@ public class CsvFeed : IFeed
         if (!File.Exists(filePath))
             throw new FileNotFoundException($"CSV file not found: {filePath}", filePath);
 
+        _filePath = filePath;
         _data = LoadFromCsv(filePath);
         _currentIndex = 0;
     }
@@ -65,37 +118,131 @@ public class CsvFeed : IFeed
 
         var series = new TBarSeries(dataLines.Count);
 
+        // Pre-allocate arrays for bulk loading (SoA layout)
+        long[] t = new long[dataLines.Count];
+        double[] o = new double[dataLines.Count];
+        double[] h = new double[dataLines.Count];
+        double[] l = new double[dataLines.Count];
+        double[] c = new double[dataLines.Count];
+        double[] v = new double[dataLines.Count];
+
         for (int i = 0; i < dataLines.Count; i++)
         {
             var line = dataLines[i];
-
-            var parts = line.Split(',');
             int originalLineNumber = dataLines.Count - i + 1;
-            if (parts.Length != 6)
-                throw new FormatException($"Invalid CSV format at line {originalLineNumber}. Expected 6 columns, found {parts.Length}");
 
-            // Parse timestamp (YYYY-MM-DD format, assume UTC midnight)
-            if (!DateTime.TryParseExact(parts[0].Trim(), "yyyy-MM-dd", CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal, out var timestamp))
-            {
-                throw new FormatException($"Failed to parse timestamp at line {originalLineNumber}: {line}");
-            }
-
-            // Parse OHLCV values
-            if (!double.TryParse(parts[1].Trim(), CultureInfo.InvariantCulture, out double open) ||
-                !double.TryParse(parts[2].Trim(), CultureInfo.InvariantCulture, out double high) ||
-                !double.TryParse(parts[3].Trim(), CultureInfo.InvariantCulture, out double low) ||
-                !double.TryParse(parts[4].Trim(), CultureInfo.InvariantCulture, out double close) ||
-                !double.TryParse(parts[5].Trim(), CultureInfo.InvariantCulture, out double volume))
-            {
-                throw new FormatException($"Failed to parse CSV line {originalLineNumber}: {line}");
-            }
-
-            series.Add(timestamp, open, high, low, close, volume, isNew: true);
+            var parsed = ParseCsvLine(line, originalLineNumber);
+            t[i] = parsed.Time;
+            o[i] = parsed.Open;
+            h[i] = parsed.High;
+            l[i] = parsed.Low;
+            c[i] = parsed.Close;
+            v[i] = parsed.Volume;
         }
 
+        // Bulk add to series
+        series.Add(t, o, h, l, c, v);
+
         return series;
     }
 
+    /// <summary>
+    /// Parses a single CSV line into OHLCV components.
+    /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static ParsedOhlcv ParseCsvLine(string line, int lineNumber)
+    {
+        // Use Span-based splitting for reduced allocations
+        ReadOnlySpan<char> lineSpan = line.AsSpan();
+
+        int col = 0;
+        int start = 0;
+        OhlcvParseState state = default;
+
+        for (int i = 0; i < lineSpan.Length; i++)
+        {
+            if (lineSpan[i] == ',')
+            {
+                var segment = lineSpan[start..i].Trim();
+                ParseColumn(segment, col, lineNumber, line, ref state);
+                col++;
+                start = i + 1;
+            }
+        }
+
+        // Process the last segment after the final comma
+        if (start <= lineSpan.Length)
+        {
+            var segment = lineSpan[start..].Trim();
+            ParseColumn(segment, col, lineNumber, line, ref state);
+            col++;
+        }
+
+        if (col != 6)
+        {
+            throw new FormatException($"Invalid CSV format at line {lineNumber}. Expected 6 columns, found {col}");
+        }
+
+        return new ParsedOhlcv(state.Time, state.Open, state.High, state.Low, state.Close, state.Volume);
+    }
+
+    /// <summary>
+    /// Parses a single column value into the appropriate OHLCV field.
+    /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static void ParseColumn(
+        ReadOnlySpan<char> segment,
+        int col,
+        int lineNumber,
+        string line,
+        ref OhlcvParseState state)
+    {
+        switch (col)
+        {
+            case 0: // Timestamp
+                if (!DateTime.TryParseExact(segment, "yyyy-MM-dd", CultureInfo.InvariantCulture,
+                    DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal, out var timestamp))
+                {
+                    throw new FormatException($"Failed to parse timestamp at line {lineNumber}: {line}");
+                }
+                state.Time = timestamp.Ticks;
+                break;
+            case 1: // Open
+                if (!double.TryParse(segment, NumberStyles.Float, CultureInfo.InvariantCulture, out state.Open))
+                {
+                    throw new FormatException($"Failed to parse open price at line {lineNumber}: {line}");
+                }
+                break;
+            case 2: // High
+                if (!double.TryParse(segment, NumberStyles.Float, CultureInfo.InvariantCulture, out state.High))
+                {
+                    throw new FormatException($"Failed to parse high price at line {lineNumber}: {line}");
+                }
+                break;
+            case 3: // Low
+                if (!double.TryParse(segment, NumberStyles.Float, CultureInfo.InvariantCulture, out state.Low))
+                {
+                    throw new FormatException($"Failed to parse low price at line {lineNumber}: {line}");
+                }
+                break;
+            case 4: // Close
+                if (!double.TryParse(segment, NumberStyles.Float, CultureInfo.InvariantCulture, out state.Close))
+                {
+                    throw new FormatException($"Failed to parse close price at line {lineNumber}: {line}");
+                }
+                break;
+            case 5: // Volume
+                if (!double.TryParse(segment, NumberStyles.Float, CultureInfo.InvariantCulture, out state.Volume))
+                {
+                    throw new FormatException($"Failed to parse volume at line {lineNumber}: {line}");
+                }
+                break;
+            default:
+                // Extra columns are ignored - this handles the default case requirement
+                break;
+        }
+    }
+
     /// <summary>
     /// Gets the next bar with full bidirectional control.
     /// When end of data reached, returns last bar and sets isNew=false.
@@ -123,11 +270,8 @@ public class CsvFeed : IFeed
             _currentIndex++;
             _hasCurrentBar = true;
         }
-        else
-        {
-            // Update current bar - CSV has no intra-bar updates, return same bar
-            // No change to _currentBar or _currentIndex
-        }
+        // else: Update current bar - CSV has no intra-bar updates, return same bar
+        // No change to _currentBar or _currentIndex
 
         return _currentBar;
     }
@@ -140,10 +284,16 @@ public class CsvFeed : IFeed
     {
         return Next(ref isNew);
     }
+
     /// <summary>
     /// Returns a filtered subset of data matching the criteria.
     /// Resets streaming position to start of returned data.
     /// </summary>
+    /// <param name="count">Number of bars to retrieve (must be positive)</param>
+    /// <param name="startTime">Starting timestamp in ticks</param>
+    /// <param name="interval">Time interval between bars</param>
+    /// <returns>A TBarSeries containing the matched bars</returns>
+    /// <exception cref="ArgumentException">Thrown when count is not positive</exception>
     public TBarSeries Fetch(int count, long startTime, TimeSpan interval)
     {
         if (count <= 0)
@@ -151,16 +301,8 @@ public class CsvFeed : IFeed
 
         var result = new TBarSeries(count);
 
-        // Find starting index
-        int startIndex = -1;
-        for (int i = 0; i < _data.Count; i++)
-        {
-            if (_data[i].Time >= startTime)
-            {
-                startIndex = i;
-                break;
-            }
-        }
+        // Find starting index using binary search for better performance
+        int startIndex = FindStartIndex(startTime);
 
         if (startIndex == -1)
             return result;
@@ -168,6 +310,7 @@ public class CsvFeed : IFeed
         // Collect bars matching interval
         long expectedTime = startTime;
         int collected = 0;
+        long tolerance = interval.Ticks / 2; // Allow 50% tolerance
 
         for (int i = startIndex; i < _data.Count && collected < count; i++)
         {
@@ -175,7 +318,6 @@ public class CsvFeed : IFeed
 
             // Check if bar time matches expected time (within tolerance)
             long timeDiff = Math.Abs(bar.Time - expectedTime);
-            long tolerance = interval.Ticks / 2; // Allow 50% tolerance
 
             if (timeDiff <= tolerance)
             {
@@ -204,4 +346,82 @@ public class CsvFeed : IFeed
 
         return result;
     }
+
+    /// <summary>
+    /// Finds the starting index for the given start time using binary search.
+    /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private int FindStartIndex(long startTime)
+    {
+        if (_data.Count == 0)
+            return -1;
+
+        // If startTime is before first bar, return 0
+        if (_data[0].Time >= startTime)
+            return 0;
+
+        // If startTime is after last bar, return -1
+        if (_data[_data.Count - 1].Time < startTime)
+            return -1;
+
+        // Binary search for the first bar >= startTime
+        int left = 0;
+        int right = _data.Count - 1;
+
+        while (left < right)
+        {
+            int mid = left + (right - left) / 2;
+
+            if (_data[mid].Time < startTime)
+                left = mid + 1;
+            else
+                right = mid;
+        }
+
+        return left;
+    }
+
+    /// <summary>
+    /// Resets the streaming position to the beginning.
+    /// </summary>
+    public void Reset()
+    {
+        _currentIndex = 0;
+        _hasCurrentBar = false;
+        _currentBar = default;
+    }
+
+    /// <summary>
+    /// Resets the streaming position to a specific index.
+    /// </summary>
+    /// <param name="index">The index to reset to (must be valid)</param>
+    /// <exception cref="ArgumentOutOfRangeException">Thrown when index is out of range</exception>
+    public void Reset(int index)
+    {
+        if (index < 0 || index > _data.Count)
+            throw new ArgumentOutOfRangeException(nameof(index), index, $"Index must be between 0 and {_data.Count}");
+
+        _currentIndex = index;
+        _hasCurrentBar = false;
+        _currentBar = default;
+    }
+
+    /// <summary>
+    /// Gets the bar at the specified index without affecting streaming position.
+    /// </summary>
+    /// <param name="index">The index of the bar to retrieve</param>
+    /// <returns>The bar at the specified index</returns>
+    /// <exception cref="ArgumentOutOfRangeException">Thrown when index is out of range</exception>
+    public TBar GetBar(int index)
+    {
+        if (index < 0 || index >= _data.Count)
+            throw new ArgumentOutOfRangeException(nameof(index), index, $"Index must be between 0 and {_data.Count - 1}");
+
+        return _data[index];
+    }
+
+    /// <summary>
+    /// Gets the underlying data series (read-only access).
+    /// </summary>
+    public TBarSeries Data => _data;
 }

lib/feeds/gbm/Gbm.Tests.cs

@@ -1,12 +1,121 @@
-
 namespace QuanTAlib.Tests;
 
 public class GBMTests
 {
+    #region Constructor Tests
+
+    [Fact]
+    public void Constructor_DefaultParameters_CreatesValidInstance()
+    {
+        var gbm = new GBM();
+
+        Assert.Equal(100.0, gbm.StartPrice);
+        Assert.Equal(0.05, gbm.Mu);
+        Assert.Equal(0.2, gbm.Sigma);
+        Assert.Equal(100.0, gbm.CurrentPrice);
+        Assert.False(gbm.HasCurrentBar);
+    }
+
+    [Fact]
+    public void Constructor_CustomParameters_SetsCorrectly()
+    {
+        var gbm = new GBM(startPrice: 50.0, mu: 0.1, sigma: 0.3, seed: 42);
+
+        Assert.Equal(50.0, gbm.StartPrice);
+        Assert.Equal(0.1, gbm.Mu);
+        Assert.Equal(0.3, gbm.Sigma);
+        Assert.Equal(50.0, gbm.CurrentPrice);
+    }
+
+    [Theory]
+    [InlineData(0)]
+    [InlineData(-1)]
+    [InlineData(-100)]
+    public void Constructor_InvalidStartPrice_ThrowsArgumentOutOfRangeException(double startPrice)
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(startPrice: startPrice));
+    }
+
+    [Fact]
+    public void Constructor_NaNStartPrice_ThrowsArgumentOutOfRangeException()
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(startPrice: double.NaN));
+    }
+
+    [Fact]
+    public void Constructor_InfinityStartPrice_ThrowsArgumentOutOfRangeException()
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(startPrice: double.PositiveInfinity));
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(startPrice: double.NegativeInfinity));
+    }
+
+    [Theory]
+    [InlineData(-0.01)]
+    [InlineData(-1)]
+    public void Constructor_NegativeSigma_ThrowsArgumentOutOfRangeException(double sigma)
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(sigma: sigma));
+    }
+
+    [Fact]
+    public void Constructor_NaNSigma_ThrowsArgumentOutOfRangeException()
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(sigma: double.NaN));
+    }
+
+    [Fact]
+    public void Constructor_InfinitySigma_ThrowsArgumentOutOfRangeException()
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(sigma: double.PositiveInfinity));
+    }
+
+    [Fact]
+    public void Constructor_NaNMu_ThrowsArgumentOutOfRangeException()
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(mu: double.NaN));
+    }
+
+    [Fact]
+    public void Constructor_InfinityMu_ThrowsArgumentOutOfRangeException()
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(mu: double.PositiveInfinity));
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(mu: double.NegativeInfinity));
+    }
+
+    [Fact]
+    public void Constructor_ZeroTimeframe_ThrowsArgumentOutOfRangeException()
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(defaultTimeframe: TimeSpan.Zero));
+    }
+
+    [Fact]
+    public void Constructor_NegativeTimeframe_ThrowsArgumentOutOfRangeException()
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => new GBM(defaultTimeframe: TimeSpan.FromMinutes(-1)));
+    }
+
+    [Fact]
+    public void Constructor_ZeroSigma_IsValid()
+    {
+        var gbm = new GBM(sigma: 0);
+        Assert.Equal(0, gbm.Sigma);
+    }
+
+    [Fact]
+    public void Constructor_NegativeMu_IsValid()
+    {
+        var gbm = new GBM(mu: -0.1);
+        Assert.Equal(-0.1, gbm.Mu);
+    }
+
+    #endregion
+
+    #region Next Method Tests
+
     [Fact]
     public void Next_DefaultParameter_GeneratesNewBar()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
 
         var bar1 = gbm.Next();
         var bar2 = gbm.Next();
@@ -18,7 +127,7 @@ public class GBMTests
     [Fact]
     public void Next_IsNewTrue_AdvancesToNewBar()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
 
         var bar1 = gbm.Next(isNew: true);
         var bar2 = gbm.Next(isNew: true);
@@ -30,7 +139,7 @@ public class GBMTests
     [Fact]
     public void Next_IsNewFalse_UpdatesCurrentBar()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
 
         var bar1 = gbm.Next(isNew: true);
         long initialTime = bar1.Time;
@@ -38,16 +147,15 @@ public class GBMTests
         var bar2 = gbm.Next(isNew: false);
 
         Assert.Equal(initialTime, bar2.Time);
-        // Price likely changed (GBM random walk)
-        Assert.NotEqual(bar1.Close, bar2.Close);
+        Assert.Equal(bar1.Open, bar2.Open);
+        // High/Low/Close/Volume may change
     }
 
     [Fact]
     public void Next_RefBool_HonorsRequest()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
 
-        // GBM always honors isNew - parameter should remain unchanged
         bool isNew1 = true;
         var bar1 = gbm.Next(ref isNew1);
         Assert.True(isNew1, "GBM should honor isNew=true request");
@@ -64,10 +172,58 @@ public class GBMTests
         Assert.NotEqual(time1, bar3.Time);
     }
 
+    [Fact]
+    public void Next_FirstCallWithIsNewFalse_GeneratesBar()
+    {
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
+
+        // First call with isNew=false should still generate a bar
+        var bar = gbm.Next(isNew: false);
+
+        Assert.True(bar.Time > 0);
+        Assert.True(bar.Open > 0);
+        Assert.True(gbm.HasCurrentBar);
+    }
+
+    [Fact]
+    public void Next_MultipleUpdates_AccumulatesVolume()
+    {
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
+
+        var bar1 = gbm.Next(isNew: true);
+        double initialVolume = bar1.Volume;
+
+        var bar2 = gbm.Next(isNew: false);
+
+        Assert.True(bar2.Volume > initialVolume, "Volume should accumulate on intra-bar updates");
+    }
+
+    [Fact]
+    public void Next_IntraBarUpdates_ExpandsHighLow()
+    {
+        var gbm = new GBM(startPrice: 100.0, sigma: 0.5, seed: 42);
+
+        var bar1 = gbm.Next(isNew: true);
+        double initialHigh = bar1.High;
+        double initialLow = bar1.Low;
+
+        // Multiple updates should potentially expand the range
+        for (int i = 0; i < 100; i++)
+        {
+            var bar = gbm.Next(isNew: false);
+            Assert.True(bar.High >= initialHigh || bar.Low <= initialLow || i > 50,
+                "High-Low range should expand or stay same with updates");
+        }
+    }
+
+    #endregion
+
+    #region Fetch Method Tests
+
     [Fact]
     public void Fetch_GeneratesCorrectCount()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
         int count = 10;
         long startTime = DateTime.UtcNow.Ticks;
         var interval = TimeSpan.FromMinutes(1);
@@ -80,13 +236,12 @@ public class GBMTests
     [Fact]
     public void Fetch_GeneratesSequentialBars()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
         long startTime = DateTime.UtcNow.Ticks;
         var interval = TimeSpan.FromMinutes(1);
 
         var series = gbm.Fetch(5, startTime, interval);
 
-        // Verify time sequence
         for (int i = 1; i < series.Count; i++)
         {
             Assert.True(series[i].Time > series[i - 1].Time);
@@ -96,13 +251,12 @@ public class GBMTests
     [Fact]
     public void Fetch_RespectsInterval()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
         var interval = TimeSpan.FromHours(1);
         long startTime = DateTime.UtcNow.Ticks;
 
         var series = gbm.Fetch(5, startTime, interval);
 
-        // Verify interval spacing
         for (int i = 1; i < series.Count; i++)
         {
             long expectedDiff = interval.Ticks;
@@ -114,7 +268,7 @@ public class GBMTests
     [Fact]
     public void Fetch_StartsAtSpecifiedTime()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
         var startTime = new DateTime(2024, 1, 1, 9, 30, 0, DateTimeKind.Utc).Ticks;
         var interval = TimeSpan.FromMinutes(5);
 
@@ -125,13 +279,43 @@ public class GBMTests
         Assert.Equal(startTime + 2 * interval.Ticks, series[2].Time);
     }
 
+    [Theory]
+    [InlineData(0)]
+    [InlineData(-1)]
+    [InlineData(-100)]
+    public void Fetch_InvalidCount_ThrowsArgumentException(int count)
+    {
+        var gbm = new GBM(startPrice: 100.0);
+        long startTime = DateTime.UtcNow.Ticks;
+        var interval = TimeSpan.FromMinutes(1);
+
+        Assert.Throws<ArgumentException>(() => gbm.Fetch(count, startTime, interval));
+    }
+
     [Fact]
-    public void Fetch_WithDifferentIntervals_WorksCorrectly()
+    public void Fetch_ZeroInterval_ThrowsArgumentOutOfRangeException()
     {
         var gbm = new GBM(startPrice: 100.0);
         long startTime = DateTime.UtcNow.Ticks;
 
-        // Test different intervals
+        Assert.Throws<ArgumentOutOfRangeException>(() => gbm.Fetch(10, startTime, TimeSpan.Zero));
+    }
+
+    [Fact]
+    public void Fetch_NegativeInterval_ThrowsArgumentOutOfRangeException()
+    {
+        var gbm = new GBM(startPrice: 100.0);
+        long startTime = DateTime.UtcNow.Ticks;
+
+        Assert.Throws<ArgumentOutOfRangeException>(() => gbm.Fetch(10, startTime, TimeSpan.FromMinutes(-1)));
+    }
+
+    [Fact]
+    public void Fetch_WithDifferentIntervals_WorksCorrectly()
+    {
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
+        long startTime = DateTime.UtcNow.Ticks;
+
         var intervals = new[] {
             TimeSpan.FromMinutes(1),
             TimeSpan.FromMinutes(5),
@@ -142,7 +326,6 @@ public class GBMTests
         {
             var series = gbm.Fetch(3, startTime, interval);
 
-            // Verify spacing
             for (int i = 1; i < series.Count; i++)
             {
                 long expectedDiff = interval.Ticks;
@@ -153,44 +336,276 @@ public class GBMTests
     }
 
     [Fact]
-    public void GeneratesRealisticOHLCV()
+    public void Fetch_LargeCount_WorksCorrectly()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
         long startTime = DateTime.UtcNow.Ticks;
         var interval = TimeSpan.FromMinutes(1);
-        var series = gbm.Fetch(10, startTime, interval);
+
+        var series = gbm.Fetch(10000, startTime, interval);
+
+        Assert.Equal(10000, series.Count);
+        Assert.All(Enumerable.Range(0, series.Count), i =>
+        {
+            Assert.True(series[i].Open > 0);
+            Assert.True(series[i].High > 0);
+            Assert.True(series[i].Low > 0);
+            Assert.True(series[i].Close > 0);
+            Assert.True(series[i].Volume > 0);
+        });
+    }
+
+    #endregion
+
+    #region OHLCV Validity Tests
+
+    [Fact]
+    public void GeneratesRealisticOHLCV()
+    {
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
+        long startTime = DateTime.UtcNow.Ticks;
+        var interval = TimeSpan.FromMinutes(1);
+        var series = gbm.Fetch(100, startTime, interval);
 
         for (int i = 0; i < series.Count; i++)
         {
             var bar = series[i];
 
             // High should be >= max(Open, Close)
-            Assert.True(bar.High >= Math.Max(bar.Open, bar.Close));
+            Assert.True(bar.High >= Math.Max(bar.Open, bar.Close),
+                $"Bar {i}: High ({bar.High}) should be >= max(Open, Close) ({Math.Max(bar.Open, bar.Close)})");
 
             // Low should be <= min(Open, Close)
-            Assert.True(bar.Low <= Math.Min(bar.Open, bar.Close));
+            Assert.True(bar.Low <= Math.Min(bar.Open, bar.Close),
+                $"Bar {i}: Low ({bar.Low}) should be <= min(Open, Close) ({Math.Min(bar.Open, bar.Close)})");
+
+            // High should be >= Low
+            Assert.True(bar.High >= bar.Low,
+                $"Bar {i}: High ({bar.High}) should be >= Low ({bar.Low})");
 
             // Volume should be positive
-            Assert.True(bar.Volume > 0);
+            Assert.True(bar.Volume > 0, $"Bar {i}: Volume should be positive");
 
-            // All prices should be positive
-            Assert.True(bar.Open > 0);
-            Assert.True(bar.High > 0);
-            Assert.True(bar.Low > 0);
-            Assert.True(bar.Close > 0);
+            // All prices should be positive and finite
+            Assert.True(double.IsFinite(bar.Open) && bar.Open > 0, $"Bar {i}: Open should be positive and finite");
+            Assert.True(double.IsFinite(bar.High) && bar.High > 0, $"Bar {i}: High should be positive and finite");
+            Assert.True(double.IsFinite(bar.Low) && bar.Low > 0, $"Bar {i}: Low should be positive and finite");
+            Assert.True(double.IsFinite(bar.Close) && bar.Close > 0, $"Bar {i}: Close should be positive and finite");
         }
     }
 
+    [Fact]
+    public void ConsecutiveCalls_MaintainContinuity()
+    {
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
+
+        var previousBar = gbm.Next();
+        var currentBar = gbm.Next();
+
+        // currentBar.Open should equal previousBar.Close (continuity)
+        Assert.Equal(previousBar.Close, currentBar.Open);
+    }
+
+    [Fact]
+    public void Fetch_MaintainsContinuity()
+    {
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
+        long startTime = DateTime.UtcNow.Ticks;
+        var interval = TimeSpan.FromMinutes(1);
+
+        var series = gbm.Fetch(10, startTime, interval);
+
+        for (int i = 1; i < series.Count; i++)
+        {
+            Assert.True(Math.Abs(series[i - 1].Close - series[i].Open) < 1e-10,
+                $"Bar {i}: Open should equal previous bar's Close for continuity");
+        }
+    }
+
+    #endregion
+
+    #region Reset Tests
+
+    [Fact]
+    public void Reset_RestoresInitialState()
+    {
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
+
+        // Generate some bars
+        gbm.Next();
+        gbm.Next();
+        gbm.Next();
+
+        Assert.NotEqual(100.0, gbm.CurrentPrice);
+        Assert.True(gbm.HasCurrentBar);
+
+        // Reset
+        gbm.Reset();
+
+        Assert.Equal(100.0, gbm.CurrentPrice);
+        Assert.False(gbm.HasCurrentBar);
+    }
+
+    [Fact]
+    public void Reset_WithStartTime_SetsSpecificTime()
+    {
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
+        long specificTime = new DateTime(2024, 1, 1, 0, 0, 0, DateTimeKind.Utc).Ticks;
+
+        gbm.Next();
+        gbm.Reset(specificTime);
+
+        var bar = gbm.Next();
+
+        // The bar time should be based on the reset time
+        Assert.True(bar.Time > specificTime);
+        Assert.Equal(100.0, bar.Open); // Should start from initial price
+    }
+
+    #endregion
+
+    #region Seeded Reproducibility Tests
+
+    [Fact]
+    public void SeededGenerator_ProducesReproducibleResults()
+    {
+        var gbm1 = new GBM(startPrice: 100.0, seed: 42);
+        var gbm2 = new GBM(startPrice: 100.0, seed: 42);
+
+        long startTime = DateTime.UtcNow.Ticks;
+        var interval = TimeSpan.FromMinutes(1);
+
+        var series1 = gbm1.Fetch(10, startTime, interval);
+        var series2 = gbm2.Fetch(10, startTime, interval);
+
+        for (int i = 0; i < series1.Count; i++)
+        {
+            Assert.Equal(series1[i].Open, series2[i].Open);
+            Assert.Equal(series1[i].High, series2[i].High);
+            Assert.Equal(series1[i].Low, series2[i].Low);
+            Assert.Equal(series1[i].Close, series2[i].Close);
+            Assert.Equal(series1[i].Volume, series2[i].Volume);
+        }
+    }
+
+    [Fact]
+    public void DifferentSeeds_ProduceDifferentResults()
+    {
+        var gbm1 = new GBM(startPrice: 100.0, seed: 42);
+        var gbm2 = new GBM(startPrice: 100.0, seed: 123);
+
+        long startTime = DateTime.UtcNow.Ticks;
+        var interval = TimeSpan.FromMinutes(1);
+
+        var series1 = gbm1.Fetch(10, startTime, interval);
+        var series2 = gbm2.Fetch(10, startTime, interval);
+
+        bool anyDifferent = false;
+        for (int i = 0; i < series1.Count; i++)
+        {
+            if (series1[i].Close != series2[i].Close)
+            {
+                anyDifferent = true;
+                break;
+            }
+        }
+
+        Assert.True(anyDifferent, "Different seeds should produce different results");
+    }
+
+    [Fact]
+    public void UnseededGenerator_ProducesVariableResults()
+    {
+        var gbm1 = new GBM(startPrice: 100.0);
+        var gbm2 = new GBM(startPrice: 100.0);
+
+        // Note: This test may occasionally fail due to randomness, but is extremely unlikely
+        var bar1 = gbm1.Next();
+        var bar2 = gbm2.Next();
+
+        // At least one value should be different
+        bool anyDifferent = bar1.Close != bar2.Close ||
+                           bar1.High != bar2.High ||
+                           bar1.Low != bar2.Low ||
+                           bar1.Volume != bar2.Volume;
+
+        Assert.True(anyDifferent, "Unseeded generators should produce different results");
+    }
+
+    #endregion
+
+    #region Drift and Volatility Tests
+
+    [Fact]
+    public void DriftAndVolatility_AffectPriceMovement()
+    {
+        var gbmLowVol = new GBM(startPrice: 100.0, mu: 0.0, sigma: 0.01, seed: 42);
+        var gbmHighVol = new GBM(startPrice: 100.0, mu: 0.0, sigma: 0.5, seed: 42);
+
+        long startTime = DateTime.UtcNow.Ticks;
+        var interval = TimeSpan.FromMinutes(1);
+        var seriesLow = gbmLowVol.Fetch(100, startTime, interval);
+        var seriesHigh = gbmHighVol.Fetch(100, startTime, interval);
+
+        // Calculate standard deviation of returns
+        double[] returnsLow = new double[99];
+        double[] returnsHigh = new double[99];
+
+        for (int i = 1; i < 100; i++)
+        {
+            returnsLow[i - 1] = Math.Log(seriesLow[i].Close / seriesLow[i - 1].Close);
+            returnsHigh[i - 1] = Math.Log(seriesHigh[i].Close / seriesHigh[i - 1].Close);
+        }
+
+        double stdLow = CalculateStdDev(returnsLow);
+        double stdHigh = CalculateStdDev(returnsHigh);
+
+        Assert.True(stdHigh > stdLow, "High volatility should produce larger return dispersion");
+    }
+
+    [Fact]
+    public void ZeroVolatility_ProducesConstantPrices()
+    {
+        var gbm = new GBM(startPrice: 100.0, mu: 0.0, sigma: 0.0, seed: 42);
+
+        long startTime = DateTime.UtcNow.Ticks;
+        var interval = TimeSpan.FromMinutes(1);
+        var series = gbm.Fetch(10, startTime, interval);
+
+        // With zero volatility and zero drift, price should stay constant
+        for (int i = 0; i < series.Count; i++)
+        {
+            Assert.Equal(100.0, series[i].Close, 10);
+        }
+    }
+
+    private static double CalculateStdDev(double[] values)
+    {
+        double mean = 0;
+        for (int i = 0; i < values.Length; i++)
+            mean += values[i];
+        mean /= values.Length;
+
+        double sumSquares = 0;
+        for (int i = 0; i < values.Length; i++)
+            sumSquares += (values[i] - mean) * (values[i] - mean);
+
+        return Math.Sqrt(sumSquares / values.Length);
+    }
+
+    #endregion
+
+    #region State Management Tests
+
     [Fact]
     public void IntraBarUpdates_ModifyCurrentBar()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
 
         var bar1 = gbm.Next(isNew: true);
         long initialTime = bar1.Time;
         double initialClose = bar1.Close;
 
-        // Loop until price changes (random walk might stay same but unlikely)
         bool changed = false;
         for (int i = 0; i < 10; i++)
         {
@@ -209,13 +624,11 @@ public class GBMTests
     [Fact]
     public void MixedStreamingAndBatch_WorksCorrectly()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
 
-        // Start with streaming
         _ = gbm.Next();
         var bar2 = gbm.Next();
 
-        // Batch generation with explicit time
         long startTime = bar2.Time + TimeSpan.FromMinutes(1).Ticks;
         var interval = TimeSpan.FromMinutes(1);
         var series = gbm.Fetch(3, startTime, interval);
@@ -223,59 +636,66 @@ public class GBMTests
         Assert.True(series[0].Time > bar2.Time);
         Assert.Equal(3, series.Count);
 
-        // Continue streaming after batch (uses internal state)
         var bar3 = gbm.Next();
         Assert.True(bar3.Time > series[2].Time);
     }
 
     [Fact]
-    public void DriftAndVolatility_AffectPriceMovement()
+    public void Fetch_ResetsStreamingState()
     {
-        // High volatility should produce more price variation
-        var gbmLowVol = new GBM(startPrice: 100.0, mu: 0.0, sigma: 0.01);
-        var gbmHighVol = new GBM(startPrice: 100.0, mu: 0.0, sigma: 0.5);
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
 
+        // Create a bar with intra-bar updates
+        gbm.Next(isNew: true);
+        gbm.Next(isNew: false);
+        Assert.True(gbm.HasCurrentBar);
+
+        // Fetch should reset streaming state
         long startTime = DateTime.UtcNow.Ticks;
-        var interval = TimeSpan.FromMinutes(1);
-        var seriesLow = gbmLowVol.Fetch(100, startTime, interval);
-        var seriesHigh = gbmHighVol.Fetch(100, startTime, interval);
+        gbm.Fetch(5, startTime, TimeSpan.FromMinutes(1));
 
-        // Calculate price ranges
-        double rangeLow = seriesLow[99].Close - seriesLow[0].Open;
-        double rangeHigh = seriesHigh[99].Close - seriesHigh[0].Open;
-
-        // High volatility should generally produce larger absolute movements
-        Assert.True(Math.Abs(rangeHigh) > Math.Abs(rangeLow) * 0.5);
+        Assert.False(gbm.HasCurrentBar);
     }
 
+    #endregion
+
+    #region IFeed Interface Tests
+
     [Fact]
-    public void ConsecutiveCalls_MaintainContinuity()
+    public void ImplementsIFeed()
     {
-        var gbm = new GBM(startPrice: 100.0);
+        IFeed feed = new GBM(startPrice: 100.0, seed: 42);
 
-        var previousBar = gbm.Next();
-        var currentBar = gbm.Next();
+        var bar1 = feed.Next(isNew: true);
+        Assert.True(bar1.Time > 0);
 
-        // currentBar.Open should equal previousBar.Close (continuity)
-        Assert.Equal(previousBar.Close, currentBar.Open);
+        var bar2 = feed.Next(isNew: true);
+        Assert.True(bar2.Time > bar1.Time);
+
+        long startTime = DateTime.UtcNow.Ticks;
+        var series = feed.Fetch(5, startTime, TimeSpan.FromMinutes(1));
+        Assert.Equal(5, series.Count);
     }
 
+    #endregion
+
+    #region Statelessness Tests
+
     [Fact]
     public void Stateless_NoHistoryStorage()
     {
         var gbm = new GBM(startPrice: 100.0);
 
-        // Generate multiple bars
         for (int i = 0; i < 100; i++)
         {
             _ = gbm.Next();
         }
 
-        // GBM should not expose any history storage
-        // Use typeof() instead of GetType() to satisfy trimming analyzer
         var type = typeof(GBM);
         var barsProperty = type.GetProperty("Bars");
 
         Assert.Null(barsProperty);
     }
+
+    #endregion
 }

lib/feeds/gbm/ValidationHelper.cs

@@ -1,19 +1,75 @@
 using System;
 using System.Collections.Generic;
+using System.Runtime.CompilerServices;
 using Xunit;
 
 namespace QuanTAlib.Tests;
 
+/// <summary>
+/// Provides validation utilities for comparing indicator results against external libraries.
+/// Contains tolerance constants and verification methods for cross-library validation.
+/// </summary>
 public static class ValidationHelper
 {
+    /// <summary>
+    /// Default tolerance for floating-point comparisons (1e-7).
+    /// Suitable for most indicator comparisons.
+    /// </summary>
     public const double DefaultTolerance = 1e-7;
+
+    /// <summary>
+    /// Tolerance for Ooples Finance library comparisons (1e-7).
+    /// May need adjustment for specific indicators with different internal precision.
+    /// </summary>
     public const double OoplesTolerance = 1e-7;
+
+    /// <summary>
+    /// Tolerance for Skender.Stock.Indicators library comparisons (1e-7).
+    /// Skender uses decimal internally, so some precision loss is expected.
+    /// </summary>
     public const double SkenderTolerance = 1e-7;
+
+    /// <summary>
+    /// Tolerance for TA-Lib (TALib.NETCore) library comparisons (1e-7).
+    /// TA-Lib uses double precision throughout.
+    /// </summary>
     public const double TalibTolerance = 1e-7;
+
+    /// <summary>
+    /// Tolerance for Tulip library comparisons (1e-7).
+    /// Note: Tulip may have 1-bar shifts due to different initialization strategies.
+    /// </summary>
     public const double TulipTolerance = 1e-7;
+
+    /// <summary>
+    /// Relative tolerance for percentage-based comparisons (0.5%).
+    /// Use when absolute tolerance is not appropriate.
+    /// </summary>
     public const double RelativeTolerance = 0.005;
 
-    public static void VerifyData<TResult>(TSeries qSeries, IReadOnlyList<TResult> sSeries, Func<TResult, double?> selector, int skip = 100, double tolerance = DefaultTolerance)
+    /// <summary>
+    /// Default number of bars to verify from the end of the series.
+    /// Using 100 bars ensures we're comparing converged values.
+    /// </summary>
+    public const int DefaultVerificationCount = 100;
+
+    /// <summary>
+    /// Verifies TSeries results against an external library's results.
+    /// Compares the last 'skip' values by default.
+    /// </summary>
+    /// <typeparam name="TResult">The type of results from the external library</typeparam>
+    /// <param name="qSeries">QuanTAlib TSeries results</param>
+    /// <param name="sSeries">External library results</param>
+    /// <param name="selector">Function to extract the comparable value from external results</param>
+    /// <param name="skip">Number of values to verify from the end (default: 100)</param>
+    /// <param name="tolerance">Tolerance for floating-point comparison</param>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void VerifyData<TResult>(
+        TSeries qSeries,
+        IReadOnlyList<TResult> sSeries,
+        Func<TResult, double?> selector,
+        int skip = DefaultVerificationCount,
+        double tolerance = DefaultTolerance)
     {
         Assert.Equal(qSeries.Count, sSeries.Count);
 
@@ -27,11 +83,22 @@ public static class ValidationHelper
 
             if (!sValue.HasValue) continue;
 
-            Assert.Equal(sValue.Value, qValue, tolerance);
+            Assert.True(
+                Math.Abs(qValue - sValue.Value) <= tolerance,
+                $"Mismatch at index {i}: QuanTAlib={qValue:G17}, External={sValue.Value:G17}, Diff={Math.Abs(qValue - sValue.Value):G17}");
         }
     }
 
-    public static void VerifyData<TResult>(IReadOnlyList<double> qResults, IReadOnlyList<TResult> sSeries, Func<TResult, double?> selector, int skip = 100, double tolerance = DefaultTolerance)
+    /// <summary>
+    /// Verifies IReadOnlyList results against an external library's results.
+    /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void VerifyData<TResult>(
+        IReadOnlyList<double> qResults,
+        IReadOnlyList<TResult> sSeries,
+        Func<TResult, double?> selector,
+        int skip = DefaultVerificationCount,
+        double tolerance = DefaultTolerance)
     {
         Assert.Equal(qResults.Count, sSeries.Count);
 
@@ -45,11 +112,22 @@ public static class ValidationHelper
 
             if (!sValue.HasValue) continue;
 
-            Assert.Equal(sValue.Value, qValue, tolerance);
+            Assert.True(
+                Math.Abs(qValue - sValue.Value) <= tolerance,
+                $"Mismatch at index {i}: QuanTAlib={qValue:G17}, External={sValue.Value:G17}, Diff={Math.Abs(qValue - sValue.Value):G17}");
         }
     }
 
-    public static void VerifyData<TResult>(double[] qOutput, IReadOnlyList<TResult> sSeries, Func<TResult, double?> selector, int skip = 100, double tolerance = DefaultTolerance)
+    /// <summary>
+    /// Verifies double array results against an external library's results.
+    /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void VerifyData<TResult>(
+        double[] qOutput,
+        IReadOnlyList<TResult> sSeries,
+        Func<TResult, double?> selector,
+        int skip = DefaultVerificationCount,
+        double tolerance = DefaultTolerance)
     {
         Assert.Equal(qOutput.Length, sSeries.Count);
 
@@ -63,11 +141,27 @@ public static class ValidationHelper
 
             if (!sValue.HasValue) continue;
 
-            Assert.Equal(sValue.Value, qValue, tolerance);
+            Assert.True(
+                Math.Abs(qValue - sValue.Value) <= tolerance,
+                $"Mismatch at index {i}: QuanTAlib={qValue:G17}, External={sValue.Value:G17}, Diff={Math.Abs(qValue - sValue.Value):G17}");
         }
     }
 
-    public static void VerifyData(TSeries qSeries, double[] tOutput, int lookback, int skip = 100, double tolerance = DefaultTolerance)
+    /// <summary>
+    /// Verifies TSeries results against TA-Lib style output with lookback offset.
+    /// </summary>
+    /// <param name="qSeries">QuanTAlib TSeries results</param>
+    /// <param name="tOutput">TA-Lib output array</param>
+    /// <param name="lookback">TA-Lib lookback period (output is shifted by this amount)</param>
+    /// <param name="skip">Number of values to verify from the end</param>
+    /// <param name="tolerance">Tolerance for floating-point comparison</param>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void VerifyData(
+        TSeries qSeries,
+        double[] tOutput,
+        int lookback,
+        int skip = DefaultVerificationCount,
+        double tolerance = DefaultTolerance)
     {
         int count = qSeries.Count;
         int start = Math.Max(0, count - skip);
@@ -83,11 +177,22 @@ public static class ValidationHelper
 
             double tValue = tOutput[tIndex];
 
-            Assert.Equal(tValue, qValue, tolerance);
+            Assert.True(
+                Math.Abs(qValue - tValue) <= tolerance,
+                $"Mismatch at index {i} (TA-Lib index {tIndex}): QuanTAlib={qValue:G17}, TA-Lib={tValue:G17}, Diff={Math.Abs(qValue - tValue):G17}");
         }
     }
 
-    public static void VerifyData(IReadOnlyList<double> qResults, double[] tOutput, int lookback, int skip = 100, double tolerance = DefaultTolerance)
+    /// <summary>
+    /// Verifies IReadOnlyList results against TA-Lib style output with lookback offset.
+    /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void VerifyData(
+        IReadOnlyList<double> qResults,
+        double[] tOutput,
+        int lookback,
+        int skip = DefaultVerificationCount,
+        double tolerance = DefaultTolerance)
     {
         int count = qResults.Count;
         int start = Math.Max(0, count - skip);
@@ -103,11 +208,22 @@ public static class ValidationHelper
 
             double tValue = tOutput[tIndex];
 
-            Assert.Equal(tValue, qValue, tolerance);
+            Assert.True(
+                Math.Abs(qValue - tValue) <= tolerance,
+                $"Mismatch at index {i} (TA-Lib index {tIndex}): QuanTAlib={qValue:G17}, TA-Lib={tValue:G17}, Diff={Math.Abs(qValue - tValue):G17}");
         }
     }
 
-    public static void VerifyData(double[] qOutput, double[] tOutput, int lookback, int skip = 100, double tolerance = DefaultTolerance)
+    /// <summary>
+    /// Verifies double array results against TA-Lib style output with lookback offset.
+    /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void VerifyData(
+        double[] qOutput,
+        double[] tOutput,
+        int lookback,
+        int skip = DefaultVerificationCount,
+        double tolerance = DefaultTolerance)
     {
         int count = qOutput.Length;
         int start = Math.Max(0, count - skip);
@@ -123,11 +239,23 @@ public static class ValidationHelper
 
             double tValue = tOutput[tIndex];
 
-            Assert.Equal(tValue, qValue, tolerance);
+            Assert.True(
+                Math.Abs(qValue - tValue) <= tolerance,
+                $"Mismatch at index {i} (TA-Lib index {tIndex}): QuanTAlib={qValue:G17}, TA-Lib={tValue:G17}, Diff={Math.Abs(qValue - tValue):G17}");
         }
     }
 
-    public static void VerifyData(TSeries qSeries, double[] tOutput, Range outRange, int lookback, int skip = 100, double tolerance = DefaultTolerance)
+    /// <summary>
+    /// Verifies TSeries results against TA-Lib style output with range and lookback.
+    /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void VerifyData(
+        TSeries qSeries,
+        double[] tOutput,
+        Range outRange,
+        int lookback,
+        int skip = DefaultVerificationCount,
+        double tolerance = DefaultTolerance)
     {
         int count = qSeries.Count;
         int start = Math.Max(0, count - skip);
@@ -144,11 +272,23 @@ public static class ValidationHelper
 
             double tValue = tOutput[tIndex];
 
-            Assert.Equal(tValue, qValue, tolerance);
+            Assert.True(
+                Math.Abs(qValue - tValue) <= tolerance,
+                $"Mismatch at index {i} (TA-Lib index {tIndex}): QuanTAlib={qValue:G17}, TA-Lib={tValue:G17}, Diff={Math.Abs(qValue - tValue):G17}");
         }
     }
 
-    public static void VerifyData(IReadOnlyList<double> qResults, double[] tOutput, Range outRange, int lookback, int skip = 100, double tolerance = DefaultTolerance)
+    /// <summary>
+    /// Verifies IReadOnlyList results against TA-Lib style output with range and lookback.
+    /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void VerifyData(
+        IReadOnlyList<double> qResults,
+        double[] tOutput,
+        Range outRange,
+        int lookback,
+        int skip = DefaultVerificationCount,
+        double tolerance = DefaultTolerance)
     {
         int count = qResults.Count;
         int start = Math.Max(0, count - skip);
@@ -165,11 +305,23 @@ public static class ValidationHelper
 
             double tValue = tOutput[tIndex];
 
-            Assert.Equal(tValue, qValue, tolerance);
+            Assert.True(
+                Math.Abs(qValue - tValue) <= tolerance,
+                $"Mismatch at index {i} (TA-Lib index {tIndex}): QuanTAlib={qValue:G17}, TA-Lib={tValue:G17}, Diff={Math.Abs(qValue - tValue):G17}");
         }
     }
 
-    public static void VerifyData(double[] qOutput, double[] tOutput, Range outRange, int lookback, int skip = 100, double tolerance = DefaultTolerance)
+    /// <summary>
+    /// Verifies double array results against TA-Lib style output with range and lookback.
+    /// </summary>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void VerifyData(
+        double[] qOutput,
+        double[] tOutput,
+        Range outRange,
+        int lookback,
+        int skip = DefaultVerificationCount,
+        double tolerance = DefaultTolerance)
     {
         int count = qOutput.Length;
         int start = Math.Max(0, count - skip);
@@ -186,7 +338,111 @@ public static class ValidationHelper
 
             double tValue = tOutput[tIndex];
 
-            Assert.Equal(tValue, qValue, tolerance);
+            Assert.True(
+                Math.Abs(qValue - tValue) <= tolerance,
+                $"Mismatch at index {i} (TA-Lib index {tIndex}): QuanTAlib={qValue:G17}, TA-Lib={tValue:G17}, Diff={Math.Abs(qValue - tValue):G17}");
         }
     }
+
+    /// <summary>
+    /// Verifies that all values in the series are finite (not NaN or Infinity).
+    /// </summary>
+    /// <param name="series">The series to verify</param>
+    /// <param name="startIndex">Starting index for verification (default: 0)</param>
+    public static void VerifyAllFinite(TSeries series, int startIndex = 0)
+    {
+        for (int i = startIndex; i < series.Count; i++)
+        {
+            Assert.True(
+                double.IsFinite(series[i].Value),
+                $"Non-finite value at index {i}: {series[i].Value}");
+        }
+    }
+
+    /// <summary>
+    /// Verifies that all values in the array are finite (not NaN or Infinity).
+    /// </summary>
+    /// <param name="values">The array to verify</param>
+    /// <param name="startIndex">Starting index for verification (default: 0)</param>
+    public static void VerifyAllFinite(double[] values, int startIndex = 0)
+    {
+        for (int i = startIndex; i < values.Length; i++)
+        {
+            Assert.True(
+                double.IsFinite(values[i]),
+                $"Non-finite value at index {i}: {values[i]}");
+        }
+    }
+
+    /// <summary>
+    /// Verifies that two series produce the same results (for consistency testing).
+    /// </summary>
+    /// <param name="series1">First series</param>
+    /// <param name="series2">Second series</param>
+    /// <param name="tolerance">Tolerance for floating-point comparison</param>
+    public static void VerifySeriesEqual(TSeries series1, TSeries series2, double tolerance = DefaultTolerance)
+    {
+        Assert.Equal(series1.Count, series2.Count);
+
+        for (int i = 0; i < series1.Count; i++)
+        {
+            Assert.True(
+                Math.Abs(series1[i].Value - series2[i].Value) <= tolerance,
+                $"Mismatch at index {i}: Series1={series1[i].Value:G17}, Series2={series2[i].Value:G17}");
+        }
+    }
+
+    /// <summary>
+    /// Calculates the maximum absolute difference between two series.
+    /// Useful for debugging tolerance issues.
+    /// </summary>
+    public static double MaxAbsoluteDifference<TResult>(
+        TSeries qSeries,
+        IReadOnlyList<TResult> sSeries,
+        Func<TResult, double?> selector)
+    {
+        if (qSeries.Count != sSeries.Count)
+            throw new ArgumentException("Series must have the same count", nameof(sSeries));
+
+        double maxDiff = 0;
+
+        for (int i = 0; i < qSeries.Count; i++)
+        {
+            double? sValue = selector(sSeries[i]);
+            if (!sValue.HasValue) continue;
+
+            double diff = Math.Abs(qSeries[i].Value - sValue.Value);
+            if (diff > maxDiff)
+                maxDiff = diff;
+        }
+
+        return maxDiff;
+    }
+
+    /// <summary>
+    /// Calculates the maximum relative difference between two series.
+    /// Useful for percentage-based tolerance testing.
+    /// </summary>
+    public static double MaxRelativeDifference<TResult>(
+        TSeries qSeries,
+        IReadOnlyList<TResult> sSeries,
+        Func<TResult, double?> selector)
+    {
+        if (qSeries.Count != sSeries.Count)
+            throw new ArgumentException("Series must have the same count", nameof(sSeries));
+
+        double maxDiff = 0;
+
+        for (int i = 0; i < qSeries.Count; i++)
+        {
+            double? sValue = selector(sSeries[i]);
+            if (!sValue.HasValue || sValue.Value == 0) continue;
+
+            double relDiff = Math.Abs((qSeries[i].Value - sValue.Value) / sValue.Value);
+            if (relDiff > maxDiff)
+                maxDiff = relDiff;
+        }
+
+        return maxDiff;
+    }
 }

lib/feeds/gbm/ValidationTestData.cs

@@ -1,42 +1,219 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using Skender.Stock.Indicators;
 
 namespace QuanTAlib.Tests;
 
+/// <summary>
+/// Provides standardized test data for validation tests.
+/// Uses GBM (Geometric Brownian Motion) to generate realistic price data
+/// and converts it to formats required by external validation libraries.
+/// </summary>
 public sealed class ValidationTestData : IDisposable
 {
+    /// <summary>
+    /// Default number of bars for validation tests.
+    /// 5000 bars ensures sufficient convergence for most indicators.
+    /// </summary>
+    public const int DefaultCount = 5000;
+
+    /// <summary>
+    /// Default starting price for generated data.
+    /// </summary>
+    public const double DefaultStartPrice = 1000.0;
+
+    /// <summary>
+    /// Default annual drift for GBM (5%).
+    /// </summary>
+    public const double DefaultMu = 0.05;
+
+    /// <summary>
+    /// Default annual volatility for GBM (200%).
+    /// High volatility ensures diverse price scenarios.
+    /// </summary>
+    public const double DefaultSigma = 2.0;
+
+    /// <summary>
+    /// Default random seed for reproducibility.
+    /// </summary>
+    public const int DefaultSeed = 123;
+
+    /// <summary>
+    /// Gets the generated bar series.
+    /// </summary>
     public TBarSeries Bars { get; }
+
+    /// <summary>
+    /// Gets the close price series.
+    /// </summary>
     public TSeries Data { get; }
+
+    /// <summary>
+    /// Gets the quotes in Skender.Stock.Indicators format.
+    /// </summary>
     public IReadOnlyList<Quote> SkenderQuotes { get; }
+
+    /// <summary>
+    /// Gets the raw close price data as a ReadOnlyMemory for span-based APIs.
+    /// </summary>
     public ReadOnlyMemory<double> RawData { get; }
 
-    public ValidationTestData(int count = 5000, double startPrice = 1000.0, double mu = 0.05, double sigma = 2.0, int seed = 123)
+    /// <summary>
+    /// Gets the raw open prices as read-only memory.
+    /// </summary>
+    public ReadOnlyMemory<double> OpenPrices { get; }
+
+    /// <summary>
+    /// Gets the raw high prices as read-only memory.
+    /// </summary>
+    public ReadOnlyMemory<double> HighPrices { get; }
+
+    /// <summary>
+    /// Gets the raw low prices as read-only memory.
+    /// </summary>
+    public ReadOnlyMemory<double> LowPrices { get; }
+
+    /// <summary>
+    /// Gets the raw close prices as read-only memory.
+    /// </summary>
+    public ReadOnlyMemory<double> ClosePrices { get; }
+
+    /// <summary>
+    /// Gets the raw volume data as read-only memory.
+    /// </summary>
+    public ReadOnlyMemory<double> VolumeData { get; }
+
+    /// <summary>
+    /// Gets the timestamps as read-only memory.
+    /// </summary>
+    public ReadOnlyMemory<long> Timestamps { get; }
+
+    /// <summary>
+    /// Gets the number of bars in the dataset.
+    /// </summary>
+    public int Count => Bars.Count;
+
+    /// <summary>
+    /// Creates validation test data with default parameters.
+    /// </summary>
+    public ValidationTestData()
+        : this(DefaultCount, DefaultStartPrice, DefaultMu, DefaultSigma, DefaultSeed)
+    {
+    }
+
+    /// <summary>
+    /// Creates validation test data with specified parameters.
+    /// </summary>
+    /// <param name="count">Number of bars to generate</param>
+    /// <param name="startPrice">Starting price</param>
+    /// <param name="mu">Annual drift rate</param>
+    /// <param name="sigma">Annual volatility</param>
+    /// <param name="seed">Random seed for reproducibility</param>
+    public ValidationTestData(
+        int count,
+        double startPrice = DefaultStartPrice,
+        double mu = DefaultMu,
+        double sigma = DefaultSigma,
+        int seed = DefaultSeed)
     {
         var gbm = new GBM(startPrice, mu, sigma, seed: seed);
         Bars = gbm.Fetch(count, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
         Data = Bars.Close;
-        RawData = Data.Select(x => x.Value).ToArray();
 
-        var quotes = new List<Quote>();
-        for (int i = 0; i < Bars.Count; i++)
+        // Extract raw arrays efficiently (avoid LINQ in hot path)
+        int barCount = Bars.Count;
+        var openPrices = new double[barCount];
+        var highPrices = new double[barCount];
+        var lowPrices = new double[barCount];
+        var closePrices = new double[barCount];
+        var volumeData = new double[barCount];
+        var timestamps = new long[barCount];
+
+        // Use span-based access for efficiency
+        var openSpan = Bars.OpenValues;
+        var highSpan = Bars.HighValues;
+        var lowSpan = Bars.LowValues;
+        var closeSpan = Bars.CloseValues;
+        var volumeSpan = Bars.VolumeValues;
+        var timeSpan = Bars.Times;
+
+        openSpan.CopyTo(openPrices);
+        highSpan.CopyTo(highPrices);
+        lowSpan.CopyTo(lowPrices);
+        closeSpan.CopyTo(closePrices);
+        volumeSpan.CopyTo(volumeData);
+        timeSpan.CopyTo(timestamps);
+
+        // Expose as ReadOnlyMemory to prevent external modification
+        OpenPrices = openPrices;
+        HighPrices = highPrices;
+        LowPrices = lowPrices;
+        ClosePrices = closePrices;
+        VolumeData = volumeData;
+        Timestamps = timestamps;
+        RawData = closePrices;
+
+        // Build Skender quotes without LINQ
+        var quotes = new Quote[barCount];
+        for (int i = 0; i < barCount; i++)
         {
-            quotes.Add(new Quote
+            quotes[i] = new Quote
             {
-                Date = new DateTime(Bars.Open.Times[i], DateTimeKind.Utc),
-                Open = (decimal)Bars.Open[i].Value,
-                High = (decimal)Bars.High[i].Value,
-                Low = (decimal)Bars.Low[i].Value,
-                Close = (decimal)Bars.Close[i].Value,
-                Volume = (decimal)Bars.Volume[i].Value
-            });
+                Date = new DateTime(timestamps[i], DateTimeKind.Utc),
+                Open = (decimal)openPrices[i],
+                High = (decimal)highPrices[i],
+                Low = (decimal)lowPrices[i],
+                Close = (decimal)closePrices[i],
+                Volume = (decimal)volumeData[i],
+            };
         }
         SkenderQuotes = quotes;
     }
 
+    /// <summary>
+    /// Creates a subset of the data for smaller tests.
+    /// </summary>
+    /// <param name="count">Number of bars to include</param>
+    /// <returns>A new ValidationTestData instance with the subset</returns>
+    public ValidationTestData CreateSubset(int count)
+    {
+        if (count <= 0 || count > Count)
+            throw new ArgumentOutOfRangeException(nameof(count), count, $"Count must be between 1 and {Count}");
+
+        return new ValidationTestData(count, DefaultStartPrice, DefaultMu, DefaultSigma, DefaultSeed);
+    }
+
+    /// <summary>
+    /// Gets the close price span for SIMD operations.
+    /// </summary>
+    public ReadOnlySpan<double> GetCloseSpan() => ClosePrices.Span;
+
+    /// <summary>
+    /// Gets the high price span for SIMD operations.
+    /// </summary>
+    public ReadOnlySpan<double> GetHighSpan() => HighPrices.Span;
+
+    /// <summary>
+    /// Gets the low price span for SIMD operations.
+    /// </summary>
+    public ReadOnlySpan<double> GetLowSpan() => LowPrices.Span;
+
+    /// <summary>
+    /// Gets the open price span for SIMD operations.
+    /// </summary>
+    public ReadOnlySpan<double> GetOpenSpan() => OpenPrices.Span;
+
+    /// <summary>
+    /// Gets the volume span for SIMD operations.
+    /// </summary>
+    public ReadOnlySpan<double> GetVolumeSpan() => VolumeData.Span;
+
+    /// <summary>
+    /// Disposes of resources (no-op, but implements pattern for test fixtures).
+    /// </summary>
     public void Dispose()
     {
-        // No resources to dispose
+        // No unmanaged resources to dispose
+        // Implemented for IDisposable pattern compatibility with test fixtures
     }
 }

lib/feeds/gbm/gbm.cs

@@ -11,10 +11,11 @@ namespace QuanTAlib;
 [SkipLocalsInit]
 #pragma warning disable S101 // Rename class 'GBM' to match pascal case naming rules
 #pragma warning disable S2245 // Random is acceptable for simulation/testing purposes
-public class GBM : IFeed
+public sealed class GBM : IFeed
 #pragma warning restore S101
 {
     private readonly Random? _rnd;
+    private readonly double _startPrice;
 
     private double _lastPrice;
     private long _lastTime;
@@ -35,14 +36,43 @@ public class GBM : IFeed
     private double _cachedZ;
     private bool _hasCachedZ;
 
+    /// <summary>
+    /// Gets the annual drift/return rate.
+    /// </summary>
+    public double Mu => _mu;
+
+    /// <summary>
+    /// Gets the annual volatility.
+    /// </summary>
+    public double Sigma => _sigma;
+
+    /// <summary>
+    /// Gets the starting price.
+    /// </summary>
+    public double StartPrice => _startPrice;
+
+    /// <summary>
+    /// Gets the current price state.
+    /// </summary>
+    public double CurrentPrice => _lastPrice;
+
+    /// <summary>
+    /// Gets whether the generator has a current bar in progress.
+    /// </summary>
+    public bool HasCurrentBar => _hasCurrentBar;
+
     /// <summary>
     /// Creates a new GBM generator.
     /// </summary>
-    /// <param name="startPrice">Initial price (default: 100.0, must be positive)</param>
-    /// <param name="mu">Annual drift/return rate (default: 0.05 = 5%)</param>
-    /// <param name="sigma">Annual volatility (default: 0.2 = 20%, must be non-negative)</param>
-    /// <param name="defaultTimeframe">Default timeframe for bars (default: 1 minute)</param>
+    /// <param name="startPrice">Initial price (default: 100.0, must be positive and finite)</param>
+    /// <param name="mu">Annual drift/return rate (default: 0.05 = 5%, must be finite)</param>
+    /// <param name="sigma">Annual volatility (default: 0.2 = 20%, must be non-negative and finite)</param>
+    /// <param name="defaultTimeframe">Default timeframe for bars (default: 1 minute, must be positive)</param>
     /// <param name="seed">Optional random seed for reproducibility (default: null for non-deterministic)</param>
+    /// <exception cref="ArgumentOutOfRangeException">
+    /// Thrown when startPrice is not positive/finite, sigma is negative/non-finite,
+    /// mu is non-finite, or defaultTimeframe is non-positive.
+    /// </exception>
     public GBM(
         double startPrice = 100.0,
         double mu = 0.05,
@@ -50,18 +80,33 @@ public class GBM : IFeed
         TimeSpan? defaultTimeframe = null,
         int? seed = null)
     {
-        ArgumentOutOfRangeException.ThrowIfNegativeOrZero(startPrice);
-        ArgumentOutOfRangeException.ThrowIfNegative(sigma);
+        // Validate startPrice
+        if (startPrice <= 0 || !double.IsFinite(startPrice))
+            throw new ArgumentOutOfRangeException(nameof(startPrice), startPrice, "Start price must be positive and finite");
+
+        // Validate mu
+        if (!double.IsFinite(mu))
+            throw new ArgumentOutOfRangeException(nameof(mu), mu, "Drift (mu) must be finite");
+
+        // Validate sigma
+        if (sigma < 0 || !double.IsFinite(sigma))
+            throw new ArgumentOutOfRangeException(nameof(sigma), sigma, "Volatility (sigma) must be non-negative and finite");
+
+        // Use provided timeframe or default to 1 minute
+        var timeframe = defaultTimeframe ?? TimeSpan.FromMinutes(1);
+
+        // Validate timeframe
+        if (timeframe <= TimeSpan.Zero)
+            throw new ArgumentOutOfRangeException(nameof(defaultTimeframe), defaultTimeframe, "Timeframe must be positive");
 
         _rnd = seed.HasValue ? new Random(seed.Value) : null;
+        _startPrice = startPrice;
         _lastPrice = startPrice;
         _lastTime = DateTime.UtcNow.Ticks;
 
         _mu = mu;
         _sigma = sigma;
 
-        // Use provided timeframe or default to 1 minute
-        var timeframe = defaultTimeframe ?? TimeSpan.FromMinutes(1);
         _defaultTimeStep = timeframe.Ticks;
 
         // Calculate dt based on timeframe (assuming 252 trading days/year, 6.5 hours/day)
@@ -72,6 +117,33 @@ public class GBM : IFeed
         _vol = sigma * Math.Sqrt(dt);
     }
 
+    /// <summary>
+    /// Resets the generator to its initial state.
+    /// </summary>
+    public void Reset()
+    {
+        _lastPrice = _startPrice;
+        _lastTime = DateTime.UtcNow.Ticks;
+        _currentBar = default;
+        _hasCurrentBar = false;
+        _cachedZ = 0;
+        _hasCachedZ = false;
+    }
+
+    /// <summary>
+    /// Resets the generator to its initial state with a specific start time.
+    /// </summary>
+    /// <param name="startTime">The start time in ticks.</param>
+    public void Reset(long startTime)
+    {
+        _lastPrice = _startPrice;
+        _lastTime = startTime;
+        _currentBar = default;
+        _hasCurrentBar = false;
+        _cachedZ = 0;
+        _hasCachedZ = false;
+    }
+
     /// <summary>
     /// Generates a random double in [0, 1) using either the seeded Random or RandomNumberGenerator.
     /// </summary>
@@ -103,6 +175,11 @@ public class GBM : IFeed
 
         double u1 = 1.0 - NextDouble();
         double u2 = 1.0 - NextDouble();
+
+        // Guard against log(0) which produces -Infinity
+        if (u1 <= double.Epsilon)
+            u1 = double.Epsilon;
+
         double mag = Math.Sqrt(-2.0 * Math.Log(u1));
         double angle = 2.0 * Math.PI * u2;
 
@@ -128,17 +205,26 @@ public class GBM : IFeed
 
             double z = NextNormal();
             double price = _lastPrice * Math.Exp(_drift + _vol * z);
+
+            // Ensure price stays positive and finite
+            if (!double.IsFinite(price) || price <= 0)
+                price = _lastPrice;
+
             double volume = 1000 + NextDouble() * 1000;
 
             double open = _lastPrice;
             double close = price;
-            double high = Math.Max(open, close) * (1.0 + Math.Abs(NextDouble()) * 0.01);
-            double low = Math.Min(open, close) * (1.0 - Math.Abs(NextDouble()) * 0.01);
 
-            // Ensure valid OHLC
+            double rnd1 = NextDouble();
+            double rnd2 = NextDouble();
+
+            double high = Math.Max(open, close) * (1.0 + rnd1 * 0.01);
+            double low = Math.Min(open, close) * (1.0 - rnd2 * 0.01);
+
+            // Ensure valid OHLC constraints
             high = Math.Max(high, Math.Max(open, close));
             low = Math.Min(low, Math.Min(open, close));
-            low = Math.Max(0.0, low);
+            low = Math.Max(double.Epsilon, low); // Ensure positive
 
             _currentBar = new TBar(currentTime, open, high, low, close, volume);
             _hasCurrentBar = true;
@@ -151,12 +237,18 @@ public class GBM : IFeed
             // Update current bar (intra-bar tick)
             double z = NextNormal();
             double price = _lastPrice * Math.Exp(_drift + _vol * z);
+
+            // Ensure price stays positive and finite
+            if (!double.IsFinite(price) || price <= 0)
+                price = _lastPrice;
+
             double additionalVolume = 1000 + NextDouble() * 1000;
 
             var bar = _currentBar;
             double newClose = price;
             double newHigh = Math.Max(bar.High, newClose);
             double newLow = Math.Min(bar.Low, newClose);
+            newLow = Math.Max(double.Epsilon, newLow); // Ensure positive
             double newVolume = bar.Volume + additionalVolume;
 
             _currentBar = new TBar(bar.Time, bar.Open, newHigh, newLow, newClose, newVolume);
@@ -179,13 +271,19 @@ public class GBM : IFeed
     /// <summary>
     /// Generates a batch of bars using optimized batch processing with explicit time parameters.
     /// </summary>
+    /// <param name="count">Number of bars to generate (must be positive)</param>
+    /// <param name="startTime">Starting timestamp in ticks</param>
+    /// <param name="interval">Time interval between bars (must be positive)</param>
+    /// <returns>A TBarSeries containing the generated bars</returns>
+    /// <exception cref="ArgumentException">Thrown when count is not positive</exception>
+    /// <exception cref="ArgumentOutOfRangeException">Thrown when interval is not positive</exception>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public TBarSeries Fetch(int count, long startTime, TimeSpan interval)
     {
         if (count <= 0)
             throw new ArgumentException("Count must be positive", nameof(count));
         if (interval <= TimeSpan.Zero)
-            throw new ArgumentOutOfRangeException(nameof(interval), "Interval must be positive");
+            throw new ArgumentOutOfRangeException(nameof(interval), interval, "Interval must be positive");
 
         var series = new TBarSeries(count);
 
@@ -212,6 +310,10 @@ public class GBM : IFeed
             double z = NextNormal();
             double price = currentPrice * Math.Exp(drift + vol * z);
 
+            // Ensure price stays positive and finite
+            if (!double.IsFinite(price) || price <= 0)
+                price = currentPrice;
+
             double open = currentPrice;
             double close = price;
 
@@ -223,13 +325,13 @@ public class GBM : IFeed
             o[i] = open;
             c[i] = close;
 
-            double high = Math.Max(open, close) * (1.0 + Math.Abs(rnd1) * 0.01);
-            double low = Math.Min(open, close) * (1.0 - Math.Abs(rnd2) * 0.01);
+            double high = Math.Max(open, close) * (1.0 + rnd1 * 0.01);
+            double low = Math.Min(open, close) * (1.0 - rnd2 * 0.01);
 
-            // Ensure valid OHLC
+            // Ensure valid OHLC constraints
             high = Math.Max(high, Math.Max(open, close));
             low = Math.Min(low, Math.Min(open, close));
-            low = Math.Max(0.0, low);
+            low = Math.Max(double.Epsilon, low); // Ensure positive
 
             h[i] = high;
             l[i] = low;
@@ -252,3 +354,4 @@ public class GBM : IFeed
         return series;
     }
 }
+#pragma warning restore S2245

lib/momentum/adx/Adx.Tests.cs

@@ -54,6 +54,28 @@ public class AdxTests
         Assert.Equal(adx2.DiMinus.Value, adx.DiMinus.Value, 1e-9);
     }
 
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var adx = new Adx(14);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 50; i++)
+            adx.Update(bars[i]);
+
+        var originalValue = adx.Last;
+
+        for (int m = 0; m < 5; m++)
+        {
+            var modified = new TBar(bars[49].Time, bars[49].Open, bars[49].High + m, bars[49].Low - m, bars[49].Close, bars[49].Volume);
+            adx.Update(modified, isNew: false);
+        }
+
+        var restored = adx.Update(bars[49], isNew: false);
+        Assert.Equal(originalValue.Value, restored.Value, 9);
+    }
+
     [Fact]
     public void Reset_Works()
     {
@@ -79,6 +101,75 @@ public class AdxTests
         Assert.True(double.IsFinite(adx.Last.Value));
     }
 
+    [Fact]
+    public void IsHot_BecomesTrueWhenBufferFull()
+    {
+        var adx = new Adx(14);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        Assert.False(adx.IsHot);
+
+        for (int i = 0; i < bars.Count; i++)
+        {
+            adx.Update(bars[i]);
+            if (adx.IsHot) break;
+        }
+
+        Assert.True(adx.IsHot);
+    }
+
+    [Fact]
+    public void NaN_Input_UsesLastValidValue()
+    {
+        var adx = new Adx(14);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 40; i++)
+            adx.Update(bars[i]);
+
+        var nanBar = new TBar(DateTime.UtcNow, double.NaN, double.NaN, double.NaN, double.NaN, 100);
+        var result = adx.Update(nanBar);
+
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var adx = new Adx(14);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 40; i++)
+            adx.Update(bars[i]);
+
+        var infBar = new TBar(DateTime.UtcNow, double.PositiveInfinity, double.PositiveInfinity, 0, 100, 100);
+        var result = adx.Update(infBar);
+
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        var gbm = new GBM(seed: 123);
+        var bars = gbm.Fetch(200, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // 1. Batch Mode
+        var batchResult = Adx.Batch(bars, 14);
+        double expected = batchResult.Last.Value;
+
+        // 2. Streaming Mode
+        var streamAdx = new Adx(14);
+        for (int i = 0; i < bars.Count; i++)
+            streamAdx.Update(bars[i]);
+        double streamResult = streamAdx.Last.Value;
+
+        Assert.Equal(expected, streamResult, 9);
+    }
+
     [Fact]
     public void TBarSeries_Update_Matches_Streaming()
     {

lib/momentum/adxr/Adxr.Tests.cs

@@ -145,4 +145,130 @@ public class AdxrTests
         var result2 = adxr.Update(bars[0]);
         Assert.IsType<TValue>(result2);
     }
+
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var adxr = new Adxr(5);
+        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1);
+
+        // Feed 20 new values
+        TBar twentiethInput = default;
+        for (int i = 0; i < 20; i++)
+        {
+            var bar = gbm.Next(isNew: true);
+            twentiethInput = bar;
+            adxr.Update(bar, isNew: true);
+        }
+
+        // Remember state after 20 values
+        double stateAfterTwenty = adxr.Last.Value;
+
+        // Generate 9 corrections with isNew=false (different values)
+        for (int i = 0; i < 9; i++)
+        {
+            var bar = gbm.Next(isNew: false);
+            adxr.Update(bar, isNew: false);
+        }
+
+        // Feed the remembered 20th input again with isNew=false
+        TValue finalResult = adxr.Update(twentiethInput, isNew: false);
+
+        // State should match the original state after 20 values
+        Assert.Equal(stateAfterTwenty, finalResult.Value, 1e-10);
+    }
+
+    [Fact]
+    public void IsHot_BecomesTrueWhenBufferFull()
+    {
+        var adxr = new Adxr(5);
+        var gbm = new GBM();
+
+        Assert.False(adxr.IsHot);
+
+        // ADXR needs more warmup than just period (ADX warmup + period)
+        // Feed bars until IsHot becomes true
+        int count = 0;
+        while (!adxr.IsHot && count < 100)
+        {
+            var bar = gbm.Next(isNew: true);
+            adxr.Update(bar, isNew: true);
+            count++;
+        }
+
+        Assert.True(adxr.IsHot);
+        Assert.True(count > 5); // Should take more than period bars
+    }
+
+    [Fact]
+    public void NaN_Input_UsesLastValidValue()
+    {
+        var adxr = new Adxr(5);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(30, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid bars first
+        for (int i = 0; i < 25; i++)
+        {
+            adxr.Update(bars[i]);
+        }
+
+        // Create a bar with NaN values
+        var nanBar = new TBar(DateTime.UtcNow, double.NaN, double.NaN, double.NaN, double.NaN, double.NaN);
+        var result = adxr.Update(nanBar);
+
+        // Should not crash and should return a finite value
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var adxr = new Adxr(5);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(30, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid bars first
+        for (int i = 0; i < 25; i++)
+        {
+            adxr.Update(bars[i]);
+        }
+
+        // Create a bar with Infinity values
+        var infBar = new TBar(DateTime.UtcNow, double.PositiveInfinity, double.PositiveInfinity, double.NegativeInfinity, double.PositiveInfinity, double.PositiveInfinity);
+        var result = adxr.Update(infBar);
+
+        // Should not crash and should return a finite value
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        // Arrange
+        int period = 5;
+        var gbm = new GBM(startPrice: 100, mu: 0.05, sigma: 0.2, seed: 123);
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // 1. Batch Mode (static method)
+        var batchSeries = Adxr.Batch(bars, period);
+        double expected = batchSeries.Last.Value;
+
+        // 2. Streaming Mode (instance, one bar at a time)
+        var streamingInd = new Adxr(period);
+        for (int i = 0; i < bars.Count; i++)
+        {
+            streamingInd.Update(bars[i]);
+        }
+        double streamingResult = streamingInd.Last.Value;
+
+        // 3. Instance Update with TBarSeries
+        var instanceInd = new Adxr(period);
+        var instanceResult = instanceInd.Update(bars);
+        double instanceValue = instanceResult.Last.Value;
+
+        // Assert all modes produce identical results
+        Assert.Equal(expected, streamingResult, precision: 9);
+        Assert.Equal(expected, instanceValue, precision: 9);
+    }
 }

lib/momentum/ao/Ao.Tests.cs

@@ -146,4 +146,130 @@ public class AoTests
         Assert.Throws<ArgumentException>(() => new Ao(5, 0));
         Assert.Throws<ArgumentException>(() => new Ao(34, 5)); // Fast >= Slow
     }
+
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var ao = new Ao(5, 34);
+        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1);
+
+        // Feed 50 new values (more than slow period)
+        TBar fiftiethInput = default;
+        for (int i = 0; i < 50; i++)
+        {
+            var bar = gbm.Next(isNew: true);
+            fiftiethInput = bar;
+            ao.Update(bar, isNew: true);
+        }
+
+        // Remember state after 50 values
+        double stateAfterFifty = ao.Last.Value;
+
+        // Generate 9 corrections with isNew=false (different values)
+        for (int i = 0; i < 9; i++)
+        {
+            var bar = gbm.Next(isNew: false);
+            ao.Update(bar, isNew: false);
+        }
+
+        // Feed the remembered 50th input again with isNew=false
+        TValue finalResult = ao.Update(fiftiethInput, isNew: false);
+
+        // State should match the original state after 50 values
+        Assert.Equal(stateAfterFifty, finalResult.Value, 1e-10);
+    }
+
+    [Fact]
+    public void IsHot_BecomesTrueWhenBufferFull()
+    {
+        var ao = new Ao(5, 34);
+        var gbm = new GBM();
+
+        Assert.False(ao.IsHot);
+
+        // Feed bars until IsHot becomes true
+        int count = 0;
+        while (!ao.IsHot && count < 100)
+        {
+            var bar = gbm.Next(isNew: true);
+            ao.Update(bar, isNew: true);
+            count++;
+        }
+
+        Assert.True(ao.IsHot);
+        Assert.True(count >= 34); // Should take at least slow period bars
+    }
+
+    [Fact]
+    public void NaN_Input_UsesLastValidValue()
+    {
+        var ao = new Ao(5, 34);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid bars first
+        for (int i = 0; i < 40; i++)
+        {
+            ao.Update(bars[i]);
+        }
+
+        // Create a bar with NaN values
+        var nanBar = new TBar(DateTime.UtcNow, double.NaN, double.NaN, double.NaN, double.NaN, double.NaN);
+        var result = ao.Update(nanBar);
+
+        // Should not crash and should return a finite value
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var ao = new Ao(5, 34);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid bars first
+        for (int i = 0; i < 40; i++)
+        {
+            ao.Update(bars[i]);
+        }
+
+        // Create a bar with Infinity values
+        var infBar = new TBar(DateTime.UtcNow, double.PositiveInfinity, double.PositiveInfinity, double.NegativeInfinity, double.PositiveInfinity, double.PositiveInfinity);
+        var result = ao.Update(infBar);
+
+        // Should not crash and should return a finite value
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        // Arrange
+        int fastPeriod = 5;
+        int slowPeriod = 34;
+        var gbm = new GBM(startPrice: 100, mu: 0.05, sigma: 0.2, seed: 123);
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // 1. Batch Mode (static method)
+        var batchSeries = Ao.Batch(bars, fastPeriod, slowPeriod);
+        double expected = batchSeries.Last.Value;
+
+        // 2. Streaming Mode (instance, one bar at a time)
+        var streamingInd = new Ao(fastPeriod, slowPeriod);
+        for (int i = 0; i < bars.Count; i++)
+        {
+            streamingInd.Update(bars[i]);
+        }
+        double streamingResult = streamingInd.Last.Value;
+
+        // 3. Instance Update with TBarSeries
+        var instanceInd = new Ao(fastPeriod, slowPeriod);
+        var instanceResult = instanceInd.Update(bars);
+        double instanceValue = instanceResult.Last.Value;
+
+        // Assert all modes produce identical results
+        Assert.Equal(expected, streamingResult, precision: 9);
+        Assert.Equal(expected, instanceValue, precision: 9);
+    }
 }

lib/momentum/apo/Apo.Tests.cs

@@ -146,4 +146,131 @@ public class ApoTests
         Assert.Throws<ArgumentException>(() => new Apo(12, 0));
         Assert.Throws<ArgumentException>(() => new Apo(26, 12)); // Fast >= Slow
     }
+
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var apo = new Apo(12, 26);
+        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1);
+
+        // Feed 50 new values (more than slow period)
+        TBar fiftiethInput = default;
+        for (int i = 0; i < 50; i++)
+        {
+            var bar = gbm.Next(isNew: true);
+            fiftiethInput = bar;
+            apo.Update(bar, isNew: true);
+        }
+
+        // Remember state after 50 values
+        double stateAfterFifty = apo.Last.Value;
+
+        // Generate 9 corrections with isNew=false (different values)
+        for (int i = 0; i < 9; i++)
+        {
+            var bar = gbm.Next(isNew: false);
+            apo.Update(bar, isNew: false);
+        }
+
+        // Feed the remembered 50th input again with isNew=false
+        TValue finalResult = apo.Update(fiftiethInput, isNew: false);
+
+        // State should match the original state after 50 values
+        Assert.Equal(stateAfterFifty, finalResult.Value, 1e-10);
+    }
+
+    [Fact]
+    public void IsHot_BecomesTrueWhenBufferFull()
+    {
+        var apo = new Apo(12, 26);
+        var gbm = new GBM();
+
+        Assert.False(apo.IsHot);
+
+        // Feed bars until IsHot becomes true
+        int count = 0;
+        while (!apo.IsHot && count < 100)
+        {
+            var bar = gbm.Next(isNew: true);
+            apo.Update(bar, isNew: true);
+            count++;
+        }
+
+        Assert.True(apo.IsHot);
+        Assert.True(count >= 26); // Should take at least slow period bars
+    }
+
+    [Fact]
+    public void NaN_Input_UsesLastValidValue()
+    {
+        var apo = new Apo(12, 26);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid bars first
+        for (int i = 0; i < 40; i++)
+        {
+            apo.Update(bars[i]);
+        }
+
+        // Create a bar with NaN close value
+        var nanBar = new TBar(DateTime.UtcNow, 100, 105, 95, double.NaN, 1000);
+        var result = apo.Update(nanBar);
+
+        // Should not crash and should return a finite value
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var apo = new Apo(12, 26);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid bars first
+        for (int i = 0; i < 40; i++)
+        {
+            apo.Update(bars[i]);
+        }
+
+        // Create a bar with Infinity close value
+        var infBar = new TBar(DateTime.UtcNow, 100, 105, 95, double.PositiveInfinity, 1000);
+        var result = apo.Update(infBar);
+
+        // Should not crash and should return a finite value
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        // Arrange
+        int fastPeriod = 12;
+        int slowPeriod = 26;
+        var gbm = new GBM(startPrice: 100, mu: 0.05, sigma: 0.2, seed: 123);
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+        var closeSeries = bars.Close;
+
+        // 1. Batch Mode (static method)
+        var batchSeries = Apo.Batch(closeSeries, fastPeriod, slowPeriod);
+        double expected = batchSeries.Last.Value;
+
+        // 2. Streaming Mode (instance, one bar at a time)
+        var streamingInd = new Apo(fastPeriod, slowPeriod);
+        for (int i = 0; i < bars.Count; i++)
+        {
+            streamingInd.Update(bars[i]);
+        }
+        double streamingResult = streamingInd.Last.Value;
+
+        // 3. Instance Update with TSeries
+        var instanceInd = new Apo(fastPeriod, slowPeriod);
+        var instanceResult = instanceInd.Update(closeSeries);
+        double instanceValue = instanceResult.Last.Value;
+
+        // Assert all modes produce identical results
+        Assert.Equal(expected, streamingResult, precision: 9);
+        Assert.Equal(expected, instanceValue, precision: 9);
+    }
 }

lib/momentum/aroon/Aroon.Tests.cs

@@ -162,4 +162,137 @@ public class AroonTests
         Assert.Equal(100.0, aroon.Down.Value, 1e-9);
         Assert.Equal(-50.0, result.Value, 1e-9);
     }
+
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var aroon = new Aroon(5);
+        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1);
+
+        // Feed 20 new values
+        TBar twentiethInput = default;
+        for (int i = 0; i < 20; i++)
+        {
+            var bar = gbm.Next(isNew: true);
+            twentiethInput = bar;
+            aroon.Update(bar, isNew: true);
+        }
+
+        // Remember state after 20 values
+        double stateAfterTwenty = aroon.Last.Value;
+        double upAfterTwenty = aroon.Up.Value;
+        double downAfterTwenty = aroon.Down.Value;
+
+        // Generate 9 corrections with isNew=false (different values)
+        for (int i = 0; i < 9; i++)
+        {
+            var bar = gbm.Next(isNew: false);
+            aroon.Update(bar, isNew: false);
+        }
+
+        // Feed the remembered 20th input again with isNew=false
+        TValue finalResult = aroon.Update(twentiethInput, isNew: false);
+
+        // State should match the original state after 20 values
+        Assert.Equal(stateAfterTwenty, finalResult.Value, 1e-10);
+        Assert.Equal(upAfterTwenty, aroon.Up.Value, 1e-10);
+        Assert.Equal(downAfterTwenty, aroon.Down.Value, 1e-10);
+    }
+
+    [Fact]
+    public void IsHot_BecomesTrueWhenBufferFull()
+    {
+        var aroon = new Aroon(5);
+        var gbm = new GBM();
+
+        Assert.False(aroon.IsHot);
+
+        // Feed bars until IsHot becomes true
+        int count = 0;
+        while (!aroon.IsHot && count < 50)
+        {
+            var bar = gbm.Next(isNew: true);
+            aroon.Update(bar, isNew: true);
+            count++;
+        }
+
+        Assert.True(aroon.IsHot);
+        Assert.True(count >= 5); // Should take at least period bars
+    }
+
+    [Fact]
+    public void NaN_Input_UsesLastValidValue()
+    {
+        var aroon = new Aroon(5);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(20, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid bars first
+        for (int i = 0; i < 15; i++)
+        {
+            aroon.Update(bars[i]);
+        }
+
+        // Create a bar with NaN values
+        var nanBar = new TBar(DateTime.UtcNow, double.NaN, double.NaN, double.NaN, double.NaN, double.NaN);
+        var result = aroon.Update(nanBar);
+
+        // Should not crash and should return a finite value
+        Assert.True(double.IsFinite(result.Value));
+        Assert.True(double.IsFinite(aroon.Up.Value));
+        Assert.True(double.IsFinite(aroon.Down.Value));
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var aroon = new Aroon(5);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(20, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid bars first
+        for (int i = 0; i < 15; i++)
+        {
+            aroon.Update(bars[i]);
+        }
+
+        // Create a bar with Infinity values
+        var infBar = new TBar(DateTime.UtcNow, double.PositiveInfinity, double.PositiveInfinity, double.NegativeInfinity, double.PositiveInfinity, double.PositiveInfinity);
+        var result = aroon.Update(infBar);
+
+        // Should not crash and should return a finite value
+        Assert.True(double.IsFinite(result.Value));
+        Assert.True(double.IsFinite(aroon.Up.Value));
+        Assert.True(double.IsFinite(aroon.Down.Value));
+    }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        // Arrange
+        int period = 14;
+        var gbm = new GBM(startPrice: 100, mu: 0.05, sigma: 0.2, seed: 123);
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // 1. Batch Mode (static method)
+        var batchSeries = Aroon.Batch(bars, period);
+        double expected = batchSeries.Last.Value;
+
+        // 2. Streaming Mode (instance, one bar at a time)
+        var streamingInd = new Aroon(period);
+        for (int i = 0; i < bars.Count; i++)
+        {
+            streamingInd.Update(bars[i]);
+        }
+        double streamingResult = streamingInd.Last.Value;
+
+        // 3. Instance Update with TBarSeries
+        var instanceInd = new Aroon(period);
+        var instanceResult = instanceInd.Update(bars);
+        double instanceValue = instanceResult.Last.Value;
+
+        // Assert all modes produce identical results
+        Assert.Equal(expected, streamingResult, precision: 9);
+        Assert.Equal(expected, instanceValue, precision: 9);
+    }
 }

lib/momentum/aroonosc/AroonOsc.Tests.cs

@@ -156,4 +156,129 @@ public class AroonOscTests
 
         Assert.Equal(-50.0, result.Value, 1e-9);
     }
+
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var aroon = new AroonOsc(5);
+        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1);
+
+        // Feed 20 new values
+        TBar twentiethInput = default;
+        for (int i = 0; i < 20; i++)
+        {
+            var bar = gbm.Next(isNew: true);
+            twentiethInput = bar;
+            aroon.Update(bar, isNew: true);
+        }
+
+        // Remember state after 20 values
+        double stateAfterTwenty = aroon.Last.Value;
+
+        // Generate 9 corrections with isNew=false (different values)
+        for (int i = 0; i < 9; i++)
+        {
+            var bar = gbm.Next(isNew: false);
+            aroon.Update(bar, isNew: false);
+        }
+
+        // Feed the remembered 20th input again with isNew=false
+        TValue finalResult = aroon.Update(twentiethInput, isNew: false);
+
+        // State should match the original state after 20 values
+        Assert.Equal(stateAfterTwenty, finalResult.Value, 1e-10);
+    }
+
+    [Fact]
+    public void IsHot_BecomesTrueWhenBufferFull()
+    {
+        var aroon = new AroonOsc(5);
+        var gbm = new GBM();
+
+        Assert.False(aroon.IsHot);
+
+        // Feed bars until IsHot becomes true
+        int count = 0;
+        while (!aroon.IsHot && count < 50)
+        {
+            var bar = gbm.Next(isNew: true);
+            aroon.Update(bar, isNew: true);
+            count++;
+        }
+
+        Assert.True(aroon.IsHot);
+        Assert.True(count >= 5); // Should take at least period bars
+    }
+
+    [Fact]
+    public void NaN_Input_UsesLastValidValue()
+    {
+        var aroon = new AroonOsc(5);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(20, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid bars first
+        for (int i = 0; i < 15; i++)
+        {
+            aroon.Update(bars[i]);
+        }
+
+        // Create a bar with NaN values
+        var nanBar = new TBar(DateTime.UtcNow, double.NaN, double.NaN, double.NaN, double.NaN, double.NaN);
+        var result = aroon.Update(nanBar);
+
+        // Should not crash and should return a finite value
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var aroon = new AroonOsc(5);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(20, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid bars first
+        for (int i = 0; i < 15; i++)
+        {
+            aroon.Update(bars[i]);
+        }
+
+        // Create a bar with Infinity values
+        var infBar = new TBar(DateTime.UtcNow, double.PositiveInfinity, double.PositiveInfinity, double.NegativeInfinity, double.PositiveInfinity, double.PositiveInfinity);
+        var result = aroon.Update(infBar);
+
+        // Should not crash and should return a finite value
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        // Arrange
+        int period = 14;
+        var gbm = new GBM(startPrice: 100, mu: 0.05, sigma: 0.2, seed: 123);
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // 1. Batch Mode (static method)
+        var batchSeries = AroonOsc.Batch(bars, period);
+        double expected = batchSeries.Last.Value;
+
+        // 2. Streaming Mode (instance, one bar at a time)
+        var streamingInd = new AroonOsc(period);
+        for (int i = 0; i < bars.Count; i++)
+        {
+            streamingInd.Update(bars[i]);
+        }
+        double streamingResult = streamingInd.Last.Value;
+
+        // 3. Instance Update with TBarSeries
+        var instanceInd = new AroonOsc(period);
+        var instanceResult = instanceInd.Update(bars);
+        double instanceValue = instanceResult.Last.Value;
+
+        // Assert all modes produce identical results
+        Assert.Equal(expected, streamingResult, precision: 9);
+        Assert.Equal(expected, instanceValue, precision: 9);
+    }
 }

lib/momentum/bop/Bop.Tests.cs

@@ -59,6 +59,116 @@ public class BopTests
         Assert.Equal(-1, result.Value);
     }
 
+    [Fact]
+    public void Calc_IsNew_AcceptsParameter()
+    {
+        // BOP is stateless - each bar is calculated independently
+        // isNew parameter is accepted but doesn't affect stateless calculation
+        var bop = new Bop();
+        // bar1: BOP = (15-10)/(20-5) = 5/15 = 0.333
+        var bar1 = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+        // bar2: BOP = (25-15)/(30-10) = 10/20 = 0.5
+        var bar2 = new TBar(DateTime.UtcNow, 15, 30, 10, 25, 100);
+
+        bop.Update(bar1, isNew: true);
+        var val1 = bop.Last.Value;
+
+        bop.Update(bar2, isNew: true);
+        var val2 = bop.Last.Value;
+
+        // Different bars produce different BOP values
+        Assert.NotEqual(val1, val2);
+        Assert.Equal(1.0 / 3.0, val1, 6); // bar1 BOP
+        Assert.Equal(0.5, val2, 6);       // bar2 BOP
+    }
+
+    [Fact]
+    public void Calc_IsNew_False_UpdatesValue()
+    {
+        // BOP is stateless - each bar is calculated independently
+        // isNew=false still calculates the new value
+        var bop = new Bop();
+        var bar1 = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+        var bar2 = new TBar(DateTime.UtcNow.AddMinutes(1), 10, 25, 5, 20, 100);
+
+        var val1 = bop.Update(bar1, isNew: true);
+        var val2 = bop.Update(bar2, isNew: false);
+
+        // Different bars produce different values (BOP has no state to preserve)
+        Assert.NotEqual(val1.Value, val2.Value);
+    }
+
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var bop = new Bop();
+        var bar = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+
+        var originalValue = bop.Update(bar, isNew: true);
+
+        for (int i = 0; i < 5; i++)
+        {
+            var modified = new TBar(bar.Time, bar.Open, bar.High + i, bar.Low, bar.Close, bar.Volume);
+            bop.Update(modified, isNew: false);
+        }
+
+        var restored = bop.Update(bar, isNew: false);
+        Assert.Equal(originalValue.Value, restored.Value, 9);
+    }
+
+    [Fact]
+    public void Reset_ClearsState()
+    {
+        var bop = new Bop();
+        var bar = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+
+        bop.Update(bar);
+        bop.Reset();
+
+        Assert.Equal(0, bop.Last.Value);
+    }
+
+    [Fact]
+    public void IsHot_AlwaysTrueForBop()
+    {
+        // BOP has no warmup - IsHot is always true (static property)
+        Assert.True(Bop.IsHot);
+
+        var bop = new Bop();
+        var bar = new TBar(DateTime.UtcNow, 10, 20, 5, 15, 100);
+        bop.Update(bar);
+
+        Assert.True(Bop.IsHot);
+    }
+
+    [Fact]
+    public void NaN_Input_ProducesNaN()
+    {
+        // BOP is stateless and doesn't track last valid value
+        // NaN input propagates through the calculation
+        var bop = new Bop();
+        var barNaN = new TBar(DateTime.UtcNow, double.NaN, 20, 5, 15, 100);
+
+        var result = bop.Update(barNaN);
+
+        // BOP = (Close - Open) / (High - Low) = (15 - NaN) / (20 - 5) = NaN
+        Assert.True(double.IsNaN(result.Value));
+    }
+
+    [Fact]
+    public void Infinity_Input_ProducesInfinity()
+    {
+        // BOP is stateless and doesn't track last valid value
+        // Infinity input propagates through the calculation
+        var bop = new Bop();
+        var barInf = new TBar(DateTime.UtcNow, double.PositiveInfinity, 20, 5, 15, 100);
+
+        var result = bop.Update(barInf);
+
+        // BOP = (Close - Open) / (High - Low) = (15 - Infinity) / (20 - 5) = -Infinity
+        Assert.True(double.IsInfinity(result.Value));
+    }
+
     [Fact]
     public void BatchMatchesStreaming()
     {
@@ -92,4 +202,48 @@ public class BopTests
         Assert.Equal(batchResult[0].Value, output[0]);
         Assert.Equal(batchResult[1].Value, output[1]);
     }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        var gbm = new GBM(seed: 123);
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // 1. Batch Mode
+        var batchResult = Bop.Batch(bars);
+        double expected = batchResult.Last.Value;
+
+        // 2. Span Mode
+        var spanOutput = new double[bars.Count];
+        Bop.Calculate(bars.Open.Values, bars.High.Values, bars.Low.Values, bars.Close.Values, spanOutput);
+        double spanResult = spanOutput[^1];
+
+        // 3. Streaming Mode
+        var streamBop = new Bop();
+        for (int i = 0; i < bars.Count; i++)
+            streamBop.Update(bars[i]);
+        double streamResult = streamBop.Last.Value;
+
+        Assert.Equal(expected, spanResult, 9);
+        Assert.Equal(expected, streamResult, 9);
+    }
+
+    [Fact]
+    public void SpanBatch_ProcessesMinimumLength()
+    {
+        // BOP.Calculate processes the minimum length of all arrays
+        // It doesn't throw when output is smaller - it just processes fewer elements
+        double[] open = [1, 2, 3];
+        double[] high = [2, 3, 4];
+        double[] low = [0, 1, 2];
+        double[] close = [1.5, 2.5, 3.5];
+        double[] smallOutput = new double[2];
+
+        // This should process 2 elements (minimum of all array lengths)
+        Bop.Calculate(open, high, low, close, smallOutput);
+
+        // Verify values are calculated for the first 2 elements
+        Assert.Equal(0.25, smallOutput[0], 6); // (1.5 - 1) / (2 - 0) = 0.5/2 = 0.25
+        Assert.Equal(0.25, smallOutput[1], 6); // (2.5 - 2) / (3 - 1) = 0.5/2 = 0.25
+    }
 }

lib/momentum/cfb/Cfb.Tests.cs

@@ -6,6 +6,24 @@ namespace QuanTAlib;
 
 public class CfbTests
 {
+    [Fact]
+    public void Constructor_EmptyLengths_UsesDefaults()
+    {
+        // Cfb uses default lengths (2, 4, ..., 192) when given empty or null lengths
+        var cfb = new Cfb(Array.Empty<int>());
+        Assert.NotNull(cfb);
+        Assert.Equal("Jurik Composite Fractal Behavior", cfb.Name);
+    }
+
+    [Fact]
+    public void Constructor_CustomLengths_Works()
+    {
+        // Cfb accepts custom lengths
+        var cfb = new Cfb(new[] { 5, 10, 20 });
+        Assert.NotNull(cfb);
+        Assert.Equal("Jurik Composite Fractal Behavior", cfb.Name);
+    }
+
     [Fact]
     public void BasicCalculation_DoesNotCrash()
     {
@@ -110,6 +128,81 @@ public class CfbTests
         Assert.Equal(val3.Value, val2.Value);
     }
 
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var cfb = new Cfb();
+        var gbm = new GBM();
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 50; i++)
+            cfb.Update(new TValue(bars.Close.Times[i], bars.Close.Values[i]));
+
+        var originalValue = cfb.Last;
+
+        for (int m = 0; m < 5; m++)
+        {
+            var modified = new TValue(bars.Close.Times[49], bars.Close.Values[49] + m);
+            cfb.Update(modified, isNew: false);
+        }
+
+        var restored = cfb.Update(new TValue(bars.Close.Times[49], bars.Close.Values[49]), isNew: false);
+        Assert.Equal(originalValue.Value, restored.Value, 9);
+    }
+
+    [Fact]
+    public void NaN_Input_UsesLastValidValue()
+    {
+        var cfb = new Cfb();
+        var gbm = new GBM();
+        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 30; i++)
+            cfb.Update(new TValue(bars.Close.Times[i], bars.Close.Values[i]));
+
+        var result = cfb.Update(new TValue(DateTime.UtcNow, double.NaN));
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var cfb = new Cfb();
+        var gbm = new GBM();
+        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 30; i++)
+            cfb.Update(new TValue(bars.Close.Times[i], bars.Close.Values[i]));
+
+        var result = cfb.Update(new TValue(DateTime.UtcNow, double.PositiveInfinity));
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        var gbm = new GBM(seed: 123);
+        var bars = gbm.Fetch(200, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // 1. Batch Mode
+        var batchResult = Cfb.Batch(bars.Close);
+        double expected = batchResult.Last.Value;
+
+        // 2. Span Mode
+        var spanOutput = new double[bars.Count];
+        Cfb.Batch(bars.Close.Values.ToArray(), spanOutput);
+        double spanResult = spanOutput[^1];
+
+        // 3. Streaming Mode
+        var streamCfb = new Cfb();
+        for (int i = 0; i < bars.Count; i++)
+            streamCfb.Update(new TValue(bars.Close.Times[i], bars.Close.Values[i]));
+        double streamResult = streamCfb.Last.Value;
+
+        Assert.Equal(expected, spanResult, 9);
+        Assert.Equal(expected, streamResult, 9);
+    }
+
     [Fact]
     public void StaticBatch_Matches_Streaming()
     {

lib/momentum/dmx/Dmx.Tests.cs

@@ -6,6 +6,17 @@ namespace QuanTAlib;
 
 public class DmxTests
 {
+    [Fact]
+    public void Constructor_InvalidParameters_ThrowsException()
+    {
+        // Dmx delegates to Jma which throws ArgumentOutOfRangeException (subclass of ArgumentException)
+        var ex1 = Assert.ThrowsAny<ArgumentException>(() => new Dmx(0));
+        Assert.Contains("period", ex1.Message, StringComparison.OrdinalIgnoreCase);
+
+        var ex2 = Assert.ThrowsAny<ArgumentException>(() => new Dmx(-1));
+        Assert.Contains("period", ex2.Message, StringComparison.OrdinalIgnoreCase);
+    }
+
     [Fact]
     public void BasicCalculation_DoesNotCrash()
     {
@@ -52,6 +63,28 @@ public class DmxTests
         Assert.Equal(val3.Value, val2.Value, 1e-9);
     }
 
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var dmx = new Dmx(14);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 50; i++)
+            dmx.Update(bars[i]);
+
+        var originalValue = dmx.Last;
+
+        for (int m = 0; m < 5; m++)
+        {
+            var modified = new TBar(bars[49].Time, bars[49].Open, bars[49].High + m, bars[49].Low - m, bars[49].Close, bars[49].Volume);
+            dmx.Update(modified, isNew: false);
+        }
+
+        var restored = dmx.Update(bars[49], isNew: false);
+        Assert.Equal(originalValue.Value, restored.Value, 9);
+    }
+
     [Fact]
     public void Reset_Works()
     {
@@ -76,6 +109,57 @@ public class DmxTests
         Assert.True(double.IsFinite(dmx.Last.Value));
     }
 
+    [Fact]
+    public void NaN_Input_UsesLastValidValue()
+    {
+        var dmx = new Dmx(14);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 30; i++)
+            dmx.Update(bars[i]);
+
+        var nanBar = new TBar(DateTime.UtcNow, double.NaN, double.NaN, double.NaN, double.NaN, 100);
+        var result = dmx.Update(nanBar);
+
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var dmx = new Dmx(14);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 30; i++)
+            dmx.Update(bars[i]);
+
+        var infBar = new TBar(DateTime.UtcNow, double.PositiveInfinity, double.PositiveInfinity, 0, 100, 100);
+        var result = dmx.Update(infBar);
+
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        var gbm = new GBM(seed: 123);
+        var bars = gbm.Fetch(200, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // 1. Batch Mode
+        var batchResult = Dmx.Batch(bars, 14);
+        double expected = batchResult.Last.Value;
+
+        // 2. Streaming Mode
+        var streamDmx = new Dmx(14);
+        for (int i = 0; i < bars.Count; i++)
+            streamDmx.Update(bars[i]);
+        double streamResult = streamDmx.Last.Value;
+
+        Assert.Equal(expected, streamResult, 9);
+    }
+
     [Fact]
     public void TBarSeries_Update_Matches_Streaming()
     {

lib/momentum/macd/Macd.Quantower.Tests.cs

@@ -26,7 +26,7 @@ public class MacdIndicatorTests
         {
             FastPeriod = 12,
             SlowPeriod = 26,
-            SignalPeriod = 9
+            SignalPeriod = 9,
         };
 
         // 26 + 9 = 35
@@ -72,7 +72,7 @@ public class MacdIndicatorTests
         {
             FastPeriod = 2,
             SlowPeriod = 5,
-            SignalPeriod = 2
+            SignalPeriod = 2,
         };
         indicator.Initialize();
 

lib/momentum/macd/Macd.Tests.cs

@@ -12,12 +12,148 @@ public class MacdTests
         Assert.False(macd.IsHot);
     }
 
+    [Fact]
+    public void Constructor_ValidParameters_Works()
+    {
+        // Macd delegates to Ema which handles validation
+        // Testing that valid parameters work correctly
+        var macd = new Macd(12, 26, 9);
+        Assert.NotNull(macd);
+        Assert.Equal("Macd(12,26,9)", macd.Name);
+        Assert.Equal(35, macd.WarmupPeriod); // max(12,26) + 9 = 35
+    }
+
+    [Fact]
+    public void Constructor_CustomParameters_Works()
+    {
+        var macd = new Macd(5, 10, 3);
+        Assert.NotNull(macd);
+        Assert.Equal("Macd(5,10,3)", macd.Name);
+        Assert.Equal(13, macd.WarmupPeriod); // max(5,10) + 3 = 13
+    }
+
+    [Fact]
+    public void Calc_IsNew_AcceptsParameter()
+    {
+        var macd = new Macd(12, 26, 9);
+        var gbm = new GBM();
+        var series = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 49; i++)
+            macd.Update(series.Close[i], isNew: true);
+
+        var val1 = macd.Update(series.Close[49], isNew: true);
+        var val2 = macd.Update(new TValue(DateTime.UtcNow, series.Close[49].Value + 1), isNew: true);
+
+        Assert.NotEqual(val1.Value, val2.Value);
+    }
+
+    [Fact]
+    public void Calc_IsNew_False_UpdatesValue()
+    {
+        var macd = new Macd(12, 26, 9);
+        var gbm = new GBM();
+        var series = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 49; i++)
+            macd.Update(series.Close[i]);
+
+        var val1 = macd.Update(series.Close[49], isNew: true);
+        var val2 = macd.Update(new TValue(series.Close[49].Time, series.Close[49].Value + 5), isNew: false);
+
+        Assert.Equal(val1.Time, val2.Time);
+        Assert.NotEqual(val1.Value, val2.Value);
+    }
+
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var macd = new Macd(12, 26, 9);
+        var gbm = new GBM();
+        var series = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 50; i++)
+            macd.Update(series.Close[i]);
+
+        var originalValue = macd.Last;
+
+        for (int m = 0; m < 5; m++)
+        {
+            var modified = new TValue(series.Close[49].Time, series.Close[49].Value + m);
+            macd.Update(modified, isNew: false);
+        }
+
+        var restored = macd.Update(series.Close[49], isNew: false);
+        Assert.Equal(originalValue.Value, restored.Value, 9);
+    }
+
+    [Fact]
+    public void Reset_ClearsState()
+    {
+        var macd = new Macd(12, 26, 9);
+        var gbm = new GBM();
+        var series = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < series.Count; i++)
+            macd.Update(series.Close[i]);
+
+        macd.Reset();
+
+        Assert.Equal(0, macd.Last.Value);
+        Assert.False(macd.IsHot);
+    }
+
+    [Fact]
+    public void IsHot_BecomesTrueWhenBufferFull()
+    {
+        var macd = new Macd(12, 26, 9);
+        var gbm = new GBM();
+        var series = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        Assert.False(macd.IsHot);
+
+        for (int i = 0; i < series.Count; i++)
+        {
+            macd.Update(series.Close[i]);
+            if (i >= 40) break;
+        }
+
+        Assert.True(macd.IsHot);
+    }
+
+    [Fact]
+    public void NaN_Input_UsesLastValidValue()
+    {
+        var macd = new Macd(12, 26, 9);
+        var gbm = new GBM();
+        var series = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 40; i++)
+            macd.Update(series.Close[i]);
+
+        var result = macd.Update(new TValue(DateTime.UtcNow, double.NaN));
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var macd = new Macd(12, 26, 9);
+        var gbm = new GBM();
+        var series = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        for (int i = 0; i < 40; i++)
+            macd.Update(series.Close[i]);
+
+        var result = macd.Update(new TValue(DateTime.UtcNow, double.PositiveInfinity));
+        Assert.True(double.IsFinite(result.Value));
+    }
+
     [Fact]
     public void BatchMatchesStreaming()
     {
         var macd = new Macd(12, 26, 9);
         var series = new TSeries();
-        // Generate some data
         for (int i = 0; i < 100; i++)
         {
             series.Add(new TValue(DateTime.UtcNow.AddMinutes(i), 100 + Math.Sin(i * 0.1) * 10));
@@ -44,7 +180,6 @@ public class MacdTests
     {
         var macd = new Macd(12, 26, 9);
         var series = new TSeries();
-        // Generate some data
         for (int i = 0; i < 100; i++)
         {
             series.Add(new TValue(DateTime.UtcNow.AddMinutes(i), 100 + Math.Sin(i * 0.1) * 10));
@@ -60,4 +195,50 @@ public class MacdTests
             Assert.Equal(batchResult[i].Value, output[i], 8);
         }
     }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        var gbm = new GBM(seed: 123);
+        var series = gbm.Fetch(200, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // 1. Batch Mode
+        var batchMacd = new Macd(12, 26, 9);
+        var batchResult = batchMacd.Update(series.Close);
+        double expected = batchResult.Last.Value;
+
+        // 2. Span Mode
+        var spanOutput = new double[series.Count];
+        Macd.Calculate(series.Close.Values, spanOutput, 12, 26);
+        double spanResult = spanOutput[^1];
+
+        // 3. Streaming Mode
+        var streamMacd = new Macd(12, 26, 9);
+        for (int i = 0; i < series.Count; i++)
+            streamMacd.Update(series.Close[i]);
+        double streamResult = streamMacd.Last.Value;
+
+        // 4. Eventing Mode
+        var pubSource = new TSeries();
+        var eventMacd = new Macd(pubSource, 12, 26, 9);
+        for (int i = 0; i < series.Count; i++)
+            pubSource.Add(series.Close[i]);
+        double eventResult = eventMacd.Last.Value;
+
+        Assert.Equal(expected, spanResult, 9);
+        Assert.Equal(expected, streamResult, 9);
+        Assert.Equal(expected, eventResult, 9);
+    }
+
+    [Fact]
+    public void SpanBatch_ValidatesInput()
+    {
+        double[] source = [1, 2, 3, 4, 5];
+        double[] output = new double[5];
+        double[] wrongSize = new double[3];
+
+        Assert.Throws<ArgumentException>(() => Macd.Calculate(source, wrongSize, 12, 26));
+        Assert.Throws<ArgumentException>(() => Macd.Calculate(source, output, 0, 26));
+        Assert.Throws<ArgumentException>(() => Macd.Calculate(source, output, 12, 0));
+    }
 }

lib/momentum/rsi/Rsi.Quantower.Tests.cs

@@ -22,7 +22,7 @@ public class RsiIndicatorTests
     {
         var indicator = new RsiIndicator
         {
-            Period = 20
+            Period = 20,
         };
 
         Assert.Equal(0, RsiIndicator.MinHistoryDepths);
@@ -35,7 +35,7 @@ public class RsiIndicatorTests
     {
         var indicator = new RsiIndicator
         {
-            Period = 20
+            Period = 20,
         };
         indicator.Initialize();
 
@@ -68,7 +68,7 @@ public class RsiIndicatorTests
     {
         var indicator = new RsiIndicator
         {
-            Period = 2 // Short period for testing
+            Period = 2, // Short period for testing
         };
         indicator.Initialize();
 

lib/momentum/rsx/Rsx.Tests.cs

@@ -127,4 +127,109 @@ public class RsxTests
         var result = rsx2.Update(new TValue(DateTime.UtcNow, 100));
         Assert.False(double.IsNaN(result.Value));
     }
+
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var rsx = new Rsx(5);
+        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1);
+
+        // Feed 20 new values
+        TValue twentiethInput = default;
+        for (int i = 0; i < 20; i++)
+        {
+            var bar = gbm.Next(isNew: true);
+            twentiethInput = new TValue(bar.Time, bar.Close);
+            rsx.Update(twentiethInput, isNew: true);
+        }
+
+        // Remember state after 20 values
+        double stateAfterTwenty = rsx.Last.Value;
+
+        // Generate 9 corrections with isNew=false (different values)
+        for (int i = 0; i < 9; i++)
+        {
+            var bar = gbm.Next(isNew: false);
+            rsx.Update(new TValue(bar.Time, bar.Close), isNew: false);
+        }
+
+        // Feed the remembered 20th input again with isNew=false
+        TValue finalResult = rsx.Update(twentiethInput, isNew: false);
+
+        // State should match the original state after 20 values
+        Assert.Equal(stateAfterTwenty, finalResult.Value, 1e-10);
+    }
+
+    [Fact]
+    public void IsHot_BecomesTrueAfterFirstValue()
+    {
+        var rsx = new Rsx(5);
+
+        Assert.False(rsx.IsHot);
+
+        // RSX uses IsInitialized for IsHot, which becomes true after first value
+        rsx.Update(new TValue(DateTime.UtcNow, 100), isNew: true);
+
+        Assert.True(rsx.IsHot);
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var rsx = new Rsx(14);
+        rsx.Update(new TValue(DateTime.UtcNow, 100));
+        rsx.Update(new TValue(DateTime.UtcNow, 110));
+
+        var resultAfterPosInf = rsx.Update(new TValue(DateTime.UtcNow, double.PositiveInfinity));
+        Assert.False(double.IsNaN(resultAfterPosInf.Value));
+        Assert.True(double.IsFinite(resultAfterPosInf.Value));
+        Assert.InRange(resultAfterPosInf.Value, 0, 100);
+
+        var resultAfterNegInf = rsx.Update(new TValue(DateTime.UtcNow, double.NegativeInfinity));
+        Assert.False(double.IsNaN(resultAfterNegInf.Value));
+        Assert.True(double.IsFinite(resultAfterNegInf.Value));
+        Assert.InRange(resultAfterNegInf.Value, 0, 100);
+    }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        // Arrange
+        int period = 14;
+        var gbm = new GBM(startPrice: 100, mu: 0.05, sigma: 0.2, seed: 123);
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+        var series = bars.Close;
+
+        // 1. Batch Mode (static method)
+        var batchSeries = Rsx.Batch(series, period);
+        double expected = batchSeries.Last.Value;
+
+        // 2. Span Mode (static method with spans)
+        var spanInput = series.Values.ToArray();
+        var spanOutput = new double[spanInput.Length];
+        Rsx.Batch(spanInput, spanOutput, period);
+        double spanResult = spanOutput[^1];
+
+        // 3. Streaming Mode (instance, one value at a time)
+        var streamingInd = new Rsx(period);
+        for (int i = 0; i < series.Count; i++)
+        {
+            streamingInd.Update(series[i]);
+        }
+        double streamingResult = streamingInd.Last.Value;
+
+        // 4. Eventing Mode (chained via ITValuePublisher)
+        var pubSource = new TSeries();
+        var eventingInd = new Rsx(pubSource, period);
+        for (int i = 0; i < series.Count; i++)
+        {
+            pubSource.Add(series[i]);
+        }
+        double eventingResult = eventingInd.Last.Value;
+
+        // Assert all modes produce identical results
+        Assert.Equal(expected, spanResult, precision: 9);
+        Assert.Equal(expected, streamingResult, precision: 9);
+        Assert.Equal(expected, eventingResult, precision: 9);
+    }
 }

lib/momentum/vel/Vel.Tests.cs

@@ -161,4 +161,119 @@ public class VelTests
         vel.Update(new TValue(DateTime.UtcNow, 100));
         Assert.False(double.IsNaN(vel2.Last.Value));
     }
+
+    [Fact]
+    public void IterativeCorrections_RestoreToOriginalState()
+    {
+        var vel = new Vel(5);
+        var gbm = new GBM(startPrice: 100.0, mu: 0.02, sigma: 0.1);
+
+        // Feed 20 new values
+        TValue twentiethInput = default;
+        for (int i = 0; i < 20; i++)
+        {
+            var bar = gbm.Next(isNew: true);
+            twentiethInput = new TValue(bar.Time, bar.Close);
+            vel.Update(twentiethInput, isNew: true);
+        }
+
+        // Remember state after 20 values
+        double stateAfterTwenty = vel.Last.Value;
+
+        // Generate 9 corrections with isNew=false (different values)
+        for (int i = 0; i < 9; i++)
+        {
+            var bar = gbm.Next(isNew: false);
+            vel.Update(new TValue(bar.Time, bar.Close), isNew: false);
+        }
+
+        // Feed the remembered 20th input again with isNew=false
+        TValue finalResult = vel.Update(twentiethInput, isNew: false);
+
+        // State should match the original state after 20 values
+        Assert.Equal(stateAfterTwenty, finalResult.Value, 1e-10);
+    }
+
+    [Fact]
+    public void NaN_Input_UsesLastValidValue()
+    {
+        var vel = new Vel(5);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(20, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid values first
+        for (int i = 0; i < 15; i++)
+        {
+            vel.Update(new TValue(bars[i].Time, bars[i].Close));
+        }
+
+        // Feed NaN
+        var result = vel.Update(new TValue(DateTime.UtcNow, double.NaN));
+
+        // Should not crash and should return a finite value
+        Assert.True(double.IsFinite(result.Value));
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var vel = new Vel(5);
+        var gbm = new GBM();
+        var bars = gbm.Fetch(20, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        // Feed some valid values first
+        for (int i = 0; i < 15; i++)
+        {
+            vel.Update(new TValue(bars[i].Time, bars[i].Close));
+        }
+
+        // Feed Infinity
+        var resultPos = vel.Update(new TValue(DateTime.UtcNow, double.PositiveInfinity));
+        Assert.True(double.IsFinite(resultPos.Value));
+
+        var resultNeg = vel.Update(new TValue(DateTime.UtcNow, double.NegativeInfinity));
+        Assert.True(double.IsFinite(resultNeg.Value));
+    }
+
+    [Fact]
+    public void AllModes_ProduceSameResult()
+    {
+        // Arrange
+        int period = 10;
+        var gbm = new GBM(startPrice: 100, mu: 0.05, sigma: 0.2, seed: 123);
+        var bars = gbm.Fetch(100, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+        var series = bars.Close;
+
+        // 1. Batch Mode (static method)
+        var batchSeries = Vel.Batch(series, period);
+        double expected = batchSeries.Last.Value;
+
+        // 2. Span Mode (static method with spans)
+        var spanInput = series.Values.ToArray();
+        var spanOutput = new double[spanInput.Length];
+        Vel.Batch(spanInput.AsSpan(), spanOutput.AsSpan(), period);
+        double spanResult = spanOutput[^1];
+
+        // 3. Streaming Mode (instance, one value at a time)
+        var streamingInd = new Vel(period);
+        for (int i = 0; i < series.Count; i++)
+        {
+            streamingInd.Update(series[i]);
+        }
+        double streamingResult = streamingInd.Last.Value;
+
+        // 4. Eventing Mode (chained via ITValuePublisher)
+        var pubSource = new TSeries();
+        var eventingInd = new Vel(pubSource, period);
+        for (int i = 0; i < series.Count; i++)
+        {
+            pubSource.Add(series[i]);
+        }
+        double eventingResult = eventingInd.Last.Value;
+
+        // Assert all modes produce identical results
+        Assert.Equal(expected, spanResult, precision: 9);
+        Assert.Equal(expected, streamingResult, precision: 9);
+        Assert.Equal(expected, eventingResult, precision: 9);
+    }
 }

lib/trends/bessel/Bessel.Quantower.Tests.cs

@@ -132,7 +132,7 @@ public class BesselIndicatorTests
             SourceType.Low,
             SourceType.Close,
             SourceType.HL2,
-            SourceType.HLC3
+            SourceType.HLC3,
         };
 
         foreach (var source in sources)

lib/trends/bessel/Bessel.cs

@@ -32,7 +32,7 @@ public sealed class Bessel : AbstractBase, IDisposable
             F2 = 0,
             LastValidValue = 0,
             Count = 0,
-            IsHot = false
+            IsHot = false,
         };
     }
 

lib/trends/ema/Ema.cs

@@ -303,7 +303,6 @@ public sealed class Ema : AbstractBase
                 else
                     val = lastValidValue;
 
-
                 state.Ema = Math.FusedMultiplyAdd(state.Ema, decay, alpha * val);
                 state.E *= decay;
 

lib/trends/pwma/Pwma.cs

@@ -65,10 +65,12 @@ public sealed class Pwma : AbstractBase
     private void Handle(object? sender, in TValueEventArgs e) => Update(e.Value, e.IsNew);
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
+#pragma warning disable RCS1032 // Remove redundant parentheses
     private double GetValidValue(double input, double lastValid)
     {
         return double.IsFinite(input) ? input : lastValid;
     }
+#pragma warning restore RCS1032
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private void UpdateLastValidValue(double val)

lib/volume/adosc/Adosc.Quantower.Tests.cs

@@ -24,7 +24,7 @@ public class AdoscIndicatorTests
     {
         var indicator = new AdoscIndicator
         {
-            SlowPeriod = 20
+            SlowPeriod = 20,
         };
 
         Assert.Equal(0, AdoscIndicator.MinHistoryDepths);
@@ -37,7 +37,7 @@ public class AdoscIndicatorTests
     {
         var indicator = new AdoscIndicator
         {
-            SlowPeriod = 40
+            SlowPeriod = 40,
         };
 
         Assert.Equal(40, indicator.SlowPeriod);

quantower/IndicatorExtensions.cs

@@ -71,7 +71,7 @@ public static class IndicatorExtensions
             SourceType.HLC3 => item => (item[PriceType.High] + item[PriceType.Low] + item[PriceType.Close]) * 0.333333333333333333,
             SourceType.OHLC4 => item => (item[PriceType.Open] + item[PriceType.High] + item[PriceType.Low] + item[PriceType.Close]) * 0.25,
             SourceType.HLCC4 => item => (item[PriceType.High] + item[PriceType.Low] + item[PriceType.Close] + item[PriceType.Close]) * 0.25,
-            _ => item => item[PriceType.Close]
+            _ => item => item[PriceType.Close],
         };
     }
 

quantower/Mocks/ChartMocks.cs

@@ -0,0 +1,14 @@
+// Mock types for TradingPlatform.BusinessLayer.Chart to enable testing
+// These are minimal implementations for unit testing purposes only
+
+namespace TradingPlatform.BusinessLayer.Chart;
+
+/// <summary>
+/// Coordinates converter interface
+/// </summary>
+public interface IChartWindowCoordinatesConverter
+{
+    DateTime GetTime(int x);
+    double GetChartX(DateTime time);
+    double GetChartY(double value);
+}

quantower/Mocks/TradingPlatformMocks.cs

@@ -4,493 +4,479 @@
 using System.Drawing;
 using TradingPlatform.BusinessLayer.Chart;
 
-namespace TradingPlatform.BusinessLayer
+namespace TradingPlatform.BusinessLayer;
+
+#region Enums
+
+/// <summary>
+/// Specifies the style of indicator line.
+/// </summary>
+public enum LineStyle
 {
-    namespace Chart
-    {
-        /// <summary>
-        /// Coordinates converter interface
-        /// </summary>
-        public interface IChartWindowCoordinatesConverter
-        {
-            DateTime GetTime(int x);
-            double GetChartX(DateTime time);
-            double GetChartY(double value);
-        }
-    }
-
-    #region Enums
-
-    /// <summary>
-    /// Specifies the style of indicator line.
-    /// </summary>
-    public enum LineStyle
-    {
-        Solid,
-        Dash,
-        Dot,
-        DashDot,
-        Histogramm,
-        Points,
-        Columns,
-        StepLine
-    }
-
-    /// <summary>
-    /// Price data types
-    /// </summary>
-    public enum PriceType
-    {
-        Open,
-        High,
-        Low,
-        Close,
-        Median,
-        Typical,
-        Weighted,
-        Bid,
-        BidSize,
-        Ask,
-        AskSize,
-        Last,
-        Volume,
-        Ticks,
-        AggressorFlag,
-        TickDirection,
-        BidTickDirection,
-        AskTickDirection,
-        OpenInterest,
-        Mark,
-        FundingRate,
-        QuoteAssetVolume
-    }
-
-    /// <summary>
-    /// Seek origin for historical data
-    /// </summary>
-    public enum SeekOriginHistory
-    {
-        Begin,
-        End
-    }
-
-    /// <summary>
-    /// Update reason for indicator
-    /// </summary>
-    public enum UpdateReason
-    {
-        Unknown,
-        HistoricalBar,
-        NewTick,
-        NewBar
-    }
-
-    /// <summary>
-    /// Indicator line marker icon type
-    /// </summary>
-    public enum IndicatorLineMarkerIconType
-    {
-        None,
-        Point,
-        Circle,
-        Square,
-        Diamond,
-        Triangle,
-        TriangleDown,
-        Cross,
-        Plus,
-        Star,
-        Flag,
-        ArrowUp,
-        ArrowDown,
-        ArrowLeft,
-        ArrowRight
-    }
-
-    #endregion
-
-    #region Attributes
-
-    /// <summary>
-    /// Attribute for input parameters
-    /// </summary>
-    [AttributeUsage(AttributeTargets.Property)]
-    public class InputParameterAttribute(
-        string name = "",
-        int sortIndex = 0,
-        double minimum = int.MinValue,
-        double maximum = int.MaxValue,
-        double increment = 0.01,
-        int decimalPlaces = 2,
-        object[]? variants = null) : Attribute
-    {
-        public string Name { get; } = name;
-        public int SortIndex { get; } = sortIndex;
-        public double Minimum { get; } = minimum;
-        public double Maximum { get; } = maximum;
-        public double Increment { get; } = increment;
-        public int DecimalPlaces { get; } = decimalPlaces;
-        public IComparable[]? Variants { get; } = variants?.Cast<IComparable>().ToArray();
-    }
-
-    #endregion
-
-    #region History Item
-
-    /// <summary>
-    /// History item interface
-    /// </summary>
-    public interface IHistoryItem
-    {
-        DateTime TimeLeft { get; }
-        long TicksLeft { get; set; }
-        long TicksRight { get; set; }
-        double this[PriceType priceType] { get; }
-    }
-
-    /// <summary>
-    /// Mock history item for testing
-    /// </summary>
-    public class MockHistoryItem : IHistoryItem
-    {
-        public DateTime TimeLeft { get; set; }
-        public long TicksLeft { get; set; }
-        public long TicksRight { get; set; }
-        public double Open { get; set; }
-        public double High { get; set; }
-        public double Low { get; set; }
-        public double Close { get; set; }
-        public double Volume { get; set; }
-
-        public double this[PriceType priceType] => priceType switch
-        {
-            PriceType.Open => Open,
-            PriceType.High => High,
-            PriceType.Low => Low,
-            PriceType.Close => Close,
-            PriceType.Volume => Volume,
-            PriceType.Median => (High + Low) / 2,
-            PriceType.Typical => (High + Low + Close) / 3,
-            PriceType.Weighted => (High + Low + Close + Close) / 4,
-            _ => Close
-        };
-    }
-
-    #endregion
-
-    #region Historical Data
-
-    /// <summary>
-    /// Mock historical data for testing
-    /// </summary>
-    public class HistoricalData
-    {
-        private readonly List<IHistoryItem> _items = [];
-
-        public int Count => _items.Count;
-
-        public IHistoryItem this[int offset, SeekOriginHistory origin = SeekOriginHistory.End]
-        {
-            get
-            {
-                int index = origin == SeekOriginHistory.End
-                    ? Count - 1 - offset
-                    : offset;
-                return _items[index];
-            }
-        }
-
-        public DateTime Time(int offset = 0, SeekOriginHistory origin = SeekOriginHistory.End)
-        {
-            return this[offset, origin].TimeLeft;
-        }
-
-        public long GetIndexByTime(long ticks)
-        {
-            for (int i = 0; i < _items.Count; i++)
-            {
-                if (_items[i].TicksLeft == ticks)
-                    return Count - 1 - i;
-            }
-            return -1;
-        }
-
-        public void Add(IHistoryItem item)
-        {
-            _items.Add(item);
-        }
-
-        public void AddBar(DateTime time, double open, double high, double low, double close, double volume = 0)
-        {
-            _items.Add(new MockHistoryItem
-            {
-                TimeLeft = time,
-                TicksLeft = time.Ticks,
-                TicksRight = time.Ticks,
-                Open = open,
-                High = high,
-                Low = low,
-                Close = close,
-                Volume = volume
-            });
-        }
-
-        public void Clear() => _items.Clear();
-    }
-
-    #endregion
-
-    #region Update Args
-
-    /// <summary>
-    /// Update arguments for indicator
-    /// </summary>
-    public class UpdateArgs(UpdateReason reason)
-    {
-        public UpdateReason Reason { get; } = reason;
-    }
-
-    #endregion
-
-    #region Line Series
-
-    /// <summary>
-    /// Base class for lines
-    /// </summary>
-    public class IndicatorLineMarker(Color color, IndicatorLineMarkerIconType icon = IndicatorLineMarkerIconType.None)
-    {
-        public Color Color { get; set; } = color;
-        public IndicatorLineMarkerIconType Icon { get; set; } = icon;
-    }
-
-    public class Line(string name, Color color, int width, LineStyle style)
-    {
-        public string Name { get; set; } = name;
-        public Color Color { get; set; } = color;
-        public int Width { get; set; } = width;
-        public LineStyle Style { get; set; } = style;
-        public bool Visible { get; set; } = true;
-    }
-
-    /// <summary>
-    /// Line series for indicator output
-    /// </summary>
-    public class LineSeries(string name, Color color, int width, LineStyle style)
-        : Line(name, color, width, style)
-    {
-        private readonly List<double> _values = [];
-        private readonly List<Color> _markers = [];
-
-        public int TimeShift { get; set; }
-        public int DrawBegin { get; set; }
-        public bool ShowLineMarker { get; set; } = true;
-
-        public double this[int offset = 0, SeekOriginHistory origin = SeekOriginHistory.End]
-        {
-            get => GetValue(offset, origin);
-            set => SetValue(value, offset, origin);
-        }
-
-        public double GetValue(int offset = 0, SeekOriginHistory origin = SeekOriginHistory.End)
-        {
-            if (_values.Count == 0)
-                return double.NaN;
-
-            int index = origin == SeekOriginHistory.End
-                ? _values.Count - 1 - offset
-                : offset;
-
-            if (index < 0 || index >= _values.Count)
-                return double.NaN;
-
-            return _values[index];
-        }
-
-        public void SetValue(double value, int offset = 0, SeekOriginHistory origin = SeekOriginHistory.End)
-        {
-            EnsureCapacity(offset + 1);
-            int index = origin == SeekOriginHistory.End
-                ? _values.Count - 1 - offset
-                : offset;
-            _values[index] = value;
-        }
-
-        public void SetMarker(int offset, Color color)
-        {
-            EnsureMarkerCapacity(offset + 1);
-            int index = _markers.Count - 1 - offset;
-            if (index >= 0 && index < _markers.Count)
-                _markers[index] = color;
-        }
-
-        public void SetMarker(int offset, IndicatorLineMarker marker)
-        {
-            SetMarker(offset, marker.Color);
-        }
-
-        internal void AddValue()
-        {
-            _values.Add(double.NaN);
-            _markers.Add(Color.Transparent);
-        }
-
-        private void EnsureCapacity(int count)
-        {
-            while (_values.Count < count)
-                _values.Add(double.NaN);
-        }
-
-        private void EnsureMarkerCapacity(int count)
-        {
-            while (_markers.Count < count)
-                _markers.Add(Color.Transparent);
-        }
-
-        public int Count => _values.Count;
-        public IReadOnlyList<double> Values => _values;
-    }
-
-    #endregion
-
-    #region Paint Chart Event Args
-
-    /// <summary>
-    /// Paint chart event arguments
-    /// </summary>
-    public class PaintChartEventArgs(Graphics graphics, Rectangle clipRectangle, int windowIndex = 0) : EventArgs
-    {
-        public Graphics Graphics { get; } = graphics;
-        public Rectangle ClipRectangle { get; } = clipRectangle;
-        public int WindowIndex { get; } = windowIndex;
-    }
-
-    #endregion
-
-    #region Chart
-
-    /// <summary>
-    /// Chart interface
-    /// </summary>
-    public interface IChart
-    {
-        ChartWindow MainWindow { get; }
-        IList<ChartWindow> Windows { get; }
-        int BarsWidth { get; }
-    }
-
-    /// <summary>
-    /// Chart window
-    /// </summary>
-    public class ChartWindow
-    {
-        public Rectangle ClientRectangle { get; set; }
-        public IChartWindowCoordinatesConverter CoordinatesConverter { get; set; } = new MockCoordinatesConverter();
-    }
-
-    /// <summary>
-    /// Mock coordinates converter
-    /// </summary>
-    public class MockCoordinatesConverter : IChartWindowCoordinatesConverter
-    {
-        public DateTime GetTime(int x) => DateTime.UtcNow;
-        public double GetChartX(DateTime time) => 0;
-        public double GetChartY(double value) => 0;
-    }
-
-    /// <summary>
-    /// Mock chart for testing
-    /// </summary>
-    public class MockChart : IChart
-    {
-        public ChartWindow MainWindow { get; } = new();
-        public IList<ChartWindow> Windows { get; } = [new ChartWindow()];
-        public int BarsWidth { get; set; } = 10;
-    }
-
-    #endregion
-
-    #region Indicator Base
-
-    /// <summary>
-    /// Watchlist indicator interface
-    /// </summary>
-    public interface IWatchlistIndicator
-    {
-        int MinHistoryDepths { get; }
-    }
-
-    /// <summary>
-    /// Base class for indicators
-    /// </summary>
-    public abstract class Indicator
-    {
-        private readonly List<LineSeries> _lineSeries = [];
-
-        public string Name { get; set; } = string.Empty;
-        public string Description { get; set; } = string.Empty;
-        public virtual string ShortName => Name;
-        public virtual string SourceCodeLink => string.Empty;
-
-        public bool SeparateWindow { get; set; }
-        public bool OnBackGround { get; set; }
-
-        public HistoricalData HistoricalData { get; set; } = new();
-        public IChart? CurrentChart { get; set; }
-
-        public int Count => HistoricalData.Count;
-
-        public IList<LineSeries> LinesSeries => _lineSeries.ToArray();
-
-        protected void AddLineSeries(LineSeries series)
-        {
-            _lineSeries.Add(series);
-        }
-
-        /// <summary>
-        /// Called when indicator is initialized
-        /// </summary>
-        protected virtual void OnInit()
-        {
-            // Intentionally empty
-        }
-
-        /// <summary>
-        /// Called on each update
-        /// </summary>
-        protected virtual void OnUpdate(UpdateArgs args)
-        {
-            // Intentionally empty
-        }
-
-        /// <summary>
-        /// Called for chart painting
-        /// </summary>
-        public virtual void OnPaintChart(PaintChartEventArgs args)
-        {
-            // Intentionally empty
-        }
-
-        /// <summary>
-        /// Initialize the indicator (for testing)
-        /// </summary>
-        public void Initialize()
-        {
-            OnInit();
-        }
-
-        /// <summary>
-        /// Process an update (for testing)
-        /// </summary>
-        public void ProcessUpdate(UpdateArgs args)
-        {
-            // Ensure line series have capacity for new data
-            foreach (var series in _lineSeries)
-            {
-                series.AddValue();
-            }
-            OnUpdate(args);
-        }
-    }
-
-    #endregion
+    Solid,
+    Dash,
+    Dot,
+    DashDot,
+    Histogramm,
+    Points,
+    Columns,
+    StepLine,
 }
+
+/// <summary>
+/// Price data types
+/// </summary>
+public enum PriceType
+{
+    Open,
+    High,
+    Low,
+    Close,
+    Median,
+    Typical,
+    Weighted,
+    Bid,
+    BidSize,
+    Ask,
+    AskSize,
+    Last,
+    Volume,
+    Ticks,
+    AggressorFlag,
+    TickDirection,
+    BidTickDirection,
+    AskTickDirection,
+    OpenInterest,
+    Mark,
+    FundingRate,
+    QuoteAssetVolume,
+}
+
+/// <summary>
+/// Seek origin for historical data
+/// </summary>
+public enum SeekOriginHistory
+{
+    Begin,
+    End,
+}
+
+/// <summary>
+/// Update reason for indicator
+/// </summary>
+public enum UpdateReason
+{
+    Unknown,
+    HistoricalBar,
+    NewTick,
+    NewBar,
+}
+
+/// <summary>
+/// Indicator line marker icon type
+/// </summary>
+public enum IndicatorLineMarkerIconType
+{
+    None,
+    Point,
+    Circle,
+    Square,
+    Diamond,
+    Triangle,
+    TriangleDown,
+    Cross,
+    Plus,
+    Star,
+    Flag,
+    ArrowUp,
+    ArrowDown,
+    ArrowLeft,
+    ArrowRight,
+}
+
+#endregion
+
+#region Attributes
+
+/// <summary>
+/// Attribute for input parameters
+/// </summary>
+[AttributeUsage(AttributeTargets.Property)]
+public class InputParameterAttribute(
+    string name = "",
+    int sortIndex = 0,
+    double minimum = int.MinValue,
+    double maximum = int.MaxValue,
+    double increment = 0.01,
+    int decimalPlaces = 2,
+    object[]? variants = null) : Attribute
+{
+    public string Name { get; } = name;
+    public int SortIndex { get; } = sortIndex;
+    public double Minimum { get; } = minimum;
+    public double Maximum { get; } = maximum;
+    public double Increment { get; } = increment;
+    public int DecimalPlaces { get; } = decimalPlaces;
+    public IComparable[]? Variants { get; } = variants?.Cast<IComparable>().ToArray();
+}
+
+#endregion
+
+#region History Item
+
+/// <summary>
+/// History item interface
+/// </summary>
+public interface IHistoryItem
+{
+    DateTime TimeLeft { get; }
+    long TicksLeft { get; set; }
+    long TicksRight { get; set; }
+    double this[PriceType priceType] { get; }
+}
+
+/// <summary>
+/// Mock history item for testing
+/// </summary>
+public class MockHistoryItem : IHistoryItem
+{
+    public DateTime TimeLeft { get; set; }
+    public long TicksLeft { get; set; }
+    public long TicksRight { get; set; }
+    public double Open { get; set; }
+    public double High { get; set; }
+    public double Low { get; set; }
+    public double Close { get; set; }
+    public double Volume { get; set; }
+
+    public double this[PriceType priceType] => priceType switch
+    {
+        PriceType.Open => Open,
+        PriceType.High => High,
+        PriceType.Low => Low,
+        PriceType.Close => Close,
+        PriceType.Volume => Volume,
+        PriceType.Median => (High + Low) / 2,
+        PriceType.Typical => (High + Low + Close) / 3,
+        PriceType.Weighted => (High + Low + Close + Close) / 4,
+        _ => Close,
+    };
+}
+
+#endregion
+
+#region Historical Data
+
+/// <summary>
+/// Mock historical data for testing
+/// </summary>
+public class HistoricalData
+{
+    private readonly List<IHistoryItem> _items = [];
+
+    public int Count => _items.Count;
+
+    public IHistoryItem this[int offset, SeekOriginHistory origin = SeekOriginHistory.End]
+    {
+        get
+        {
+            int index = origin == SeekOriginHistory.End
+                ? Count - 1 - offset
+                : offset;
+            return _items[index];
+        }
+    }
+
+    public DateTime Time(int offset = 0, SeekOriginHistory origin = SeekOriginHistory.End)
+    {
+        return this[offset, origin].TimeLeft;
+    }
+
+    public long GetIndexByTime(long ticks)
+    {
+        for (int i = 0; i < _items.Count; i++)
+        {
+            if (_items[i].TicksLeft == ticks)
+                return Count - 1 - i;
+        }
+        return -1;
+    }
+
+    public void Add(IHistoryItem item)
+    {
+        _items.Add(item);
+    }
+
+    public void AddBar(DateTime time, double open, double high, double low, double close, double volume = 0)
+    {
+        _items.Add(new MockHistoryItem
+        {
+            TimeLeft = time,
+            TicksLeft = time.Ticks,
+            TicksRight = time.Ticks,
+            Open = open,
+            High = high,
+            Low = low,
+            Close = close,
+            Volume = volume
+        });
+    }
+
+    public void Clear() => _items.Clear();
+}
+
+#endregion
+
+#region Update Args
+
+/// <summary>
+/// Update arguments for indicator
+/// </summary>
+public class UpdateArgs(UpdateReason reason)
+{
+    public UpdateReason Reason { get; } = reason;
+}
+
+#endregion
+
+#region Line Series
+
+/// <summary>
+/// Base class for lines
+/// </summary>
+public class IndicatorLineMarker(Color color, IndicatorLineMarkerIconType icon = IndicatorLineMarkerIconType.None)
+{
+    public Color Color { get; set; } = color;
+    public IndicatorLineMarkerIconType Icon { get; set; } = icon;
+}
+
+public class Line(string name, Color color, int width, LineStyle style)
+{
+    public string Name { get; set; } = name;
+    public Color Color { get; set; } = color;
+    public int Width { get; set; } = width;
+    public LineStyle Style { get; set; } = style;
+    public bool Visible { get; set; } = true;
+}
+
+/// <summary>
+/// Line series for indicator output
+/// </summary>
+public class LineSeries(string name, Color color, int width, LineStyle style)
+    : Line(name, color, width, style)
+{
+    private readonly List<double> _values = [];
+    private readonly List<Color> _markers = [];
+
+    public int TimeShift { get; set; }
+    public int DrawBegin { get; set; }
+    public bool ShowLineMarker { get; set; } = true;
+
+    public double this[int offset = 0, SeekOriginHistory origin = SeekOriginHistory.End]
+    {
+        get => GetValue(offset, origin);
+        set => SetValue(value, offset, origin);
+    }
+
+    public double GetValue(int offset = 0, SeekOriginHistory origin = SeekOriginHistory.End)
+    {
+        if (_values.Count == 0)
+            return double.NaN;
+
+        int index = origin == SeekOriginHistory.End
+            ? _values.Count - 1 - offset
+            : offset;
+
+        if (index < 0 || index >= _values.Count)
+            return double.NaN;
+
+        return _values[index];
+    }
+
+    public void SetValue(double value, int offset = 0, SeekOriginHistory origin = SeekOriginHistory.End)
+    {
+        EnsureCapacity(offset + 1);
+        int index = origin == SeekOriginHistory.End
+            ? _values.Count - 1 - offset
+            : offset;
+        _values[index] = value;
+    }
+
+    public void SetMarker(int offset, Color color)
+    {
+        EnsureMarkerCapacity(offset + 1);
+        int index = _markers.Count - 1 - offset;
+        if (index >= 0 && index < _markers.Count)
+            _markers[index] = color;
+    }
+
+    public void SetMarker(int offset, IndicatorLineMarker marker)
+    {
+        SetMarker(offset, marker.Color);
+    }
+
+    internal void AddValue()
+    {
+        _values.Add(double.NaN);
+        _markers.Add(Color.Transparent);
+    }
+
+    private void EnsureCapacity(int count)
+    {
+        while (_values.Count < count)
+            _values.Add(double.NaN);
+    }
+
+    private void EnsureMarkerCapacity(int count)
+    {
+        while (_markers.Count < count)
+            _markers.Add(Color.Transparent);
+    }
+
+    public int Count => _values.Count;
+    public IReadOnlyList<double> Values => _values;
+}
+
+#endregion
+
+#region Paint Chart Event Args
+
+/// <summary>
+/// Paint chart event arguments
+/// </summary>
+public class PaintChartEventArgs(Graphics graphics, Rectangle clipRectangle, int windowIndex = 0) : EventArgs
+{
+    public Graphics Graphics { get; } = graphics;
+    public Rectangle ClipRectangle { get; } = clipRectangle;
+    public int WindowIndex { get; } = windowIndex;
+}
+
+#endregion
+
+#region Chart
+
+/// <summary>
+/// Chart interface
+/// </summary>
+public interface IChart
+{
+    ChartWindow MainWindow { get; }
+    IList<ChartWindow> Windows { get; }
+    int BarsWidth { get; }
+}
+
+/// <summary>
+/// Chart window
+/// </summary>
+public class ChartWindow
+{
+    public Rectangle ClientRectangle { get; set; }
+    public IChartWindowCoordinatesConverter CoordinatesConverter { get; set; } = new MockCoordinatesConverter();
+}
+
+/// <summary>
+/// Mock coordinates converter
+/// </summary>
+public class MockCoordinatesConverter : IChartWindowCoordinatesConverter
+{
+    public DateTime GetTime(int x) => DateTime.UtcNow;
+    public double GetChartX(DateTime time) => 0;
+    public double GetChartY(double value) => 0;
+}
+
+/// <summary>
+/// Mock chart for testing
+/// </summary>
+public class MockChart : IChart
+{
+    public ChartWindow MainWindow { get; } = new();
+    public IList<ChartWindow> Windows { get; } = [new ChartWindow()];
+    public int BarsWidth { get; set; } = 10;
+}
+
+#endregion
+
+#region Indicator Base
+
+/// <summary>
+/// Watchlist indicator interface
+/// </summary>
+public interface IWatchlistIndicator
+{
+    int MinHistoryDepths { get; }
+}
+
+/// <summary>
+/// Base class for indicators
+/// </summary>
+public abstract class Indicator
+{
+    private readonly List<LineSeries> _lineSeries = [];
+
+    public string Name { get; set; } = string.Empty;
+    public string Description { get; set; } = string.Empty;
+    public virtual string ShortName => Name;
+    public virtual string SourceCodeLink => string.Empty;
+
+    public bool SeparateWindow { get; set; }
+    public bool OnBackGround { get; set; }
+
+    public HistoricalData HistoricalData { get; set; } = new();
+    public IChart? CurrentChart { get; set; }
+
+    public int Count => HistoricalData.Count;
+
+    public IList<LineSeries> LinesSeries => _lineSeries.ToArray();
+
+    protected void AddLineSeries(LineSeries series)
+    {
+        _lineSeries.Add(series);
+    }
+
+    /// <summary>
+    /// Called when indicator is initialized
+    /// </summary>
+    protected virtual void OnInit()
+    {
+        // Intentionally empty
+    }
+
+    /// <summary>
+    /// Called on each update
+    /// </summary>
+    protected virtual void OnUpdate(UpdateArgs args)
+    {
+        // Intentionally empty
+    }
+
+    /// <summary>
+    /// Called for chart painting
+    /// </summary>
+    public virtual void OnPaintChart(PaintChartEventArgs args)
+    {
+        // Intentionally empty
+    }
+
+    /// <summary>
+    /// Initialize the indicator (for testing)
+    /// </summary>
+    public void Initialize()
+    {
+        OnInit();
+    }
+
+    /// <summary>
+    /// Process an update (for testing)
+    /// </summary>
+    public void ProcessUpdate(UpdateArgs args)
+    {
+        // Ensure line series have capacity for new data
+        foreach (var series in _lineSeries)
+        {
+            series.AddValue();
+        }
+        OnUpdate(args);
+    }
+}
+
+#endregion