test: stabilize full test collection

tests/test_topic_analyzer.py

@@ -1,8 +1,25 @@
 """Tests for topic keyword matching (src/topic_analyzer.py)."""
+import sys
 from types import SimpleNamespace
 import pytest
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
+
+
+def _drop_fake_core_database():
+    parent = sys.modules.get("core")
+    attr = getattr(parent, "database", None) if parent is not None else None
+    mod = sys.modules.get("core.database") or attr
+    if mod is None or isinstance(getattr(mod, "__file__", None), str):
+        return
+    sys.modules.pop("core.database", None)
+    sys.modules.pop("src.database", None)
+    if parent is not None and attr is mod:
+        delattr(parent, "database")
+
+
+_drop_fake_core_database()
+
 from core.database import Base, Session as DbSession, ChatMessage as DbChatMessage
 from core.session_manager import SessionManager
 from src.topic_analyzer import analyze_topics