feat: implement real-time SSE event architecture with Redis stream integration and add associated validation tests

tests/test_realtime_event_store_factory.py

@@ -0,0 +1,55 @@
+import pytest
+
+from web.realtime_event_store import RealtimeEventStore
+from web.realtime_event_store_factory import create_realtime_event_store
+from web.redis_realtime_event_store import RedisRealtimeEventStore
+
+
+class FakeRedis:
+    pass
+
+
+def test_event_store_factory_uses_sqlite_by_default(monkeypatch, tmp_path):
+    monkeypatch.delenv("POLYWEATHER_EVENT_STORE", raising=False)
+
+    store = create_realtime_event_store(db_path=str(tmp_path / "polyweather.db"))
+
+    assert isinstance(store, RealtimeEventStore)
+
+
+def test_event_store_factory_uses_redis_when_configured(monkeypatch):
+    monkeypatch.setenv("POLYWEATHER_EVENT_STORE", "redis")
+
+    store = create_realtime_event_store(redis_client=FakeRedis())
+
+    assert isinstance(store, RedisRealtimeEventStore)
+
+
+def test_event_store_factory_falls_back_to_sqlite_when_redis_is_optional(monkeypatch, tmp_path):
+    monkeypatch.setenv("POLYWEATHER_EVENT_STORE", "redis")
+    monkeypatch.setenv("POLYWEATHER_REDIS_REQUIRED", "false")
+
+    def broken_redis_store(**_kwargs):
+        raise RuntimeError("redis down")
+
+    store = create_realtime_event_store(
+        db_path=str(tmp_path / "polyweather.db"),
+        redis_store_builder=broken_redis_store,
+    )
+
+    assert isinstance(store, RealtimeEventStore)
+    assert getattr(store, "degraded_from", None) == "redis"
+
+
+def test_event_store_factory_raises_when_redis_is_required(monkeypatch, tmp_path):
+    monkeypatch.setenv("POLYWEATHER_EVENT_STORE", "redis")
+    monkeypatch.setenv("POLYWEATHER_REDIS_REQUIRED", "true")
+
+    def broken_redis_store(**_kwargs):
+        raise RuntimeError("redis down")
+
+    with pytest.raises(RuntimeError, match="redis down"):
+        create_realtime_event_store(
+            db_path=str(tmp_path / "polyweather.db"),
+            redis_store_builder=broken_redis_store,
+        )