test: stabilize full test collection

tests/test_calendar_rrule.py

@@ -6,6 +6,7 @@ calling do_manage_calendar with an rrule stores a single event carrying that RRU
 """
 
 import json
+import sys
 import tempfile
 import uuid
 
@@ -14,6 +15,21 @@ from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
 from sqlalchemy.pool import NullPool
 
+
+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()
+
 import core.database as cdb
 from core.database import CalendarEvent
 
@@ -32,6 +48,10 @@ def _bind_temp_db(monkeypatch):
     # do_manage_calendar does `from core.database import SessionLocal` at call
     # time, so patch the module attribute to our temp DB — via monkeypatch so it
     # is RESTORED after each test and can't leak into later tests in the process.
+    monkeypatch.setitem(sys.modules, "core.database", cdb)
+    parent = sys.modules.get("core")
+    if parent is not None:
+        monkeypatch.setattr(parent, "database", cdb, raising=False)
     monkeypatch.setattr(cdb, "SessionLocal", _TS)
     yield