test: reduce test_trading.py duplication with parametrize (#64)

* test: reduce test_trading.py duplication with parametrize

Collapse repetitive individual tests in test_trading.py into
parametrized equivalents, cutting 267 lines without losing any cases.

- TestExtractTickPrice: 13 tests → 2 parametrized (×3 valid, ×10 None)
- TestEstimateOrderMargin: 4 invalid-margin tests → 1 parametrized ×4;
  nan/inf volume tests → 1 parametrized ×2
- TestNormalizeOrderVolume: multi-assert bodies split into parametrized
  cases for non-finite volume and constraints
- TestVolumeAndExecution: 9 place_market_order retcode tests → 1 ×11;
  5 update_sltp retcode tests → 1 ×5
- test_calculate_trailing_stop_updates_missing_symbol_digits:
  inline double-assert body → 1 parametrized ×2

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* test: further reduce test_trading.py duplication with parametrize

Merge six broker stop-level tests into two parametrized tests, collapse
two default-digits fallback tests and three symbol-filter zero-margin
tests into one each.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* test: address claude[bot] review on PR #64

- Consolidate _MISSING_RETCODE sentinel to one line with corrected comment
- Add comment explaining ids list is required for deterministic node IDs
- Document intentional narrower retcode coverage in update_sltp test

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* test: reduce duplication in test_sdk, test_history, test_contracts

- TestBuildConfigWholeDollarEnv: 3 field tests (server/password/path) → 1
  parametrized ×3
- TestResolveAccountSpec: whole-dollar expand/no-expand pair → 1 parametrized ×2
- test_normalize_mt5_exception_maps_types: 2 isinstance asserts → parametrized ×2
- test_resolve_history_tick_flags_invalid: 2 pytest.raises blocks → parametrized ×2

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: agent <agent@localhost>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_contracts.py

@@ -234,16 +234,19 @@ def test_is_recoverable_mt5_error(exc: Exception) -> None:
     assert is_recoverable_mt5_error(exc)
 
 
-def test_normalize_mt5_exception_maps_types() -> None:
+@pytest.mark.parametrize(
+    ("exc", "expected_type"),
+    [
+        (Mt5RuntimeError("x"), Mt5ConnectionError),
+        (Mt5TradingError("x"), Mt5OperationError),
+    ],
+)
+def test_normalize_mt5_exception_maps_types(
+    exc: Exception,
+    expected_type: type[Mt5ConnectionError | Mt5OperationError],
+) -> None:
     """MT5 exceptions map to stable mt5cli types."""
-    assert isinstance(
-        normalize_mt5_exception(Mt5RuntimeError("x")),
-        Mt5ConnectionError,
-    )
-    assert isinstance(
-        normalize_mt5_exception(Mt5TradingError("x")),
-        Mt5OperationError,
-    )
+    assert isinstance(normalize_mt5_exception(exc), expected_type)
 
 
 def test_call_with_normalized_errors_reraises_mapped_type() -> None:
@@ -420,26 +423,24 @@ def test_normalize_time_columns_skips_absent_time_fields() -> None:
     assert list(result.columns) == ["open"]
 
 
-def test_normalize_time_columns_converts_unix_seconds() -> None:
-    """Numeric MT5 ``time`` values are interpreted as Unix seconds."""
-    frame = pd.DataFrame({"time": [1704067200]})
-    result = normalize_time_columns(frame, DataKind.rates)
-    assert result.loc[0, "time"] == pd.Timestamp("2024-01-01T00:00:00+00:00")
-
-
-def test_normalize_time_columns_converts_unix_milliseconds() -> None:
-    """Numeric MT5 ``time_msc`` values are interpreted as Unix milliseconds."""
-    frame = pd.DataFrame({"time_msc": [1704067200000]})
-    result = normalize_time_columns(frame, DataKind.ticks)
-    assert result.loc[0, "time_msc"] == pd.Timestamp("2024-01-01T00:00:00+00:00")
-
-
-def test_normalize_time_columns_preserves_utc_datetimes() -> None:
-    """Already-converted datetime values remain UTC-normalized."""
-    aware = datetime(2024, 1, 1, tzinfo=UTC)
-    frame = pd.DataFrame({"time": [aware]})
-    result = normalize_time_columns(frame, DataKind.rates)
-    assert result.loc[0, "time"] == pd.Timestamp("2024-01-01T00:00:00+00:00")
+@pytest.mark.parametrize(
+    ("col", "value", "kind"),
+    [
+        ("time", 1704067200, DataKind.rates),
+        ("time_msc", 1704067200000, DataKind.ticks),
+        ("time", datetime(2024, 1, 1, tzinfo=UTC), DataKind.rates),
+        ("time", "2024-01-01T00:00:00+00:00", DataKind.rates),
+    ],
+)
+def test_normalize_time_columns_coerces_value(
+    col: str,
+    value: object,
+    kind: DataKind,
+) -> None:
+    """Time column values are coerced to UTC timestamps regardless of input type."""
+    frame = pd.DataFrame({col: [value]})
+    result = normalize_time_columns(frame, kind)
+    assert result.loc[0, col] == pd.Timestamp("2024-01-01T00:00:00+00:00")
 
 
 def test_normalize_time_columns_handles_optional_order_times() -> None:
@@ -489,13 +490,6 @@ def test_ensure_utc_columns_skips_missing_columns() -> None:
     assert "time" in result.columns
 
 
-def test_normalize_time_columns_coerces_string_timestamps() -> None:
-    """String timestamps are parsed with timezone-aware datetime coercion."""
-    frame = pd.DataFrame({"time": ["2024-01-01T00:00:00+00:00"]})
-    result = normalize_time_columns(frame, DataKind.rates)
-    assert result.loc[0, "time"] == pd.Timestamp("2024-01-01T00:00:00+00:00")
-
-
 def test_ensure_utc_columns_coerces_non_mt5_columns() -> None:
     """Non-MT5 columns still coerce to UTC datetimes."""
     frame = pd.DataFrame({"created_at": ["2024-01-01T00:00:00+00:00"]})