refactor(tests): add temp sqlite helper (#2930)

tests/README.md

@@ -72,6 +72,16 @@ Use only for the guarded fake/stub `src.endpoint_resolver` cleanup pattern.
   cached against them.
 - Accepts explicit extra dependent module names to evict alongside the defaults.
 
+### `tests.helpers.sqlite_db.make_temp_sqlite`
+
+Use for the repeated file-backed temp sqlite setup in tests.
+
+- Only constructs `(SessionLocal, engine, tmpfile)` from the repeated block.
+- Does not patch modules and does not clean up the temp file.
+- The caller must bind `SessionLocal` explicitly onto whatever module the code
+  under test reads, and must keep the returned objects alive.
+- Do not use it as a general DB fixture framework.
+
 ## What not to abstract yet
 
 Some remaining patterns should stay as-is for now rather than being forced into

tests/helpers/sqlite_db.py

@@ -0,0 +1,29 @@
+"""Construct a file-backed temp sqlite DB for tests.
+
+Only builds the SQLAlchemy objects from the repeated temp-sqlite block. It
+does not patch modules, manage cleanup, or own any global state — the caller
+keeps the returned objects alive and binds ``SessionLocal`` where needed.
+"""
+import tempfile
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+from sqlalchemy.pool import NullPool
+
+
+def make_temp_sqlite(metadata):
+    """Build a file-backed temp sqlite database and create its tables.
+
+    Returns ``(SessionLocal, engine, tmpfile)``. The caller must keep these
+    references alive (temp file and engine GC are the caller's concern) and
+    bind ``SessionLocal`` onto whatever module the code under test reads.
+    """
+    tmpfile = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
+    engine = create_engine(
+        f"sqlite:///{tmpfile.name}",
+        connect_args={"check_same_thread": False},
+        poolclass=NullPool,
+    )
+    metadata.create_all(engine)
+    SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False)
+    return SessionLocal, engine, tmpfile

tests/test_calendar_rrule.py

@@ -7,29 +7,19 @@ calling do_manage_calendar with an rrule stores a single event carrying that RRU
 
 import json
 import sys
-import tempfile
 import uuid
 
 import pytest
-from sqlalchemy import create_engine
-from sqlalchemy.orm import sessionmaker
-from sqlalchemy.pool import NullPool
 
 from tests.helpers.import_state import clear_fake_database_modules
+from tests.helpers.sqlite_db import make_temp_sqlite
 
 clear_fake_database_modules()
 
 import core.database as cdb
 from core.database import CalendarEvent
 
-_TMPDB = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
+_TS, _ENGINE, _TMPDB = make_temp_sqlite(cdb.Base.metadata)
-_ENGINE = create_engine(
-    f"sqlite:///{_TMPDB.name}",
-    connect_args={"check_same_thread": False},
-    poolclass=NullPool,
-)
-cdb.Base.metadata.create_all(_ENGINE)
-_TS = sessionmaker(bind=_ENGINE, autoflush=False, autocommit=False)
 
 
 @pytest.fixture(autouse=True)

tests/test_calendar_update_event_tz.py

@@ -9,25 +9,15 @@ Tokyo user) and left is_utc inconsistent. The do_manage_notes update path
 was already fixed for the analogous issue.
 """
 import json
-import tempfile
 import uuid
 
 import pytest
-from sqlalchemy import create_engine
-from sqlalchemy.orm import sessionmaker
-from sqlalchemy.pool import NullPool
 
 import core.database as cdb
 from core.database import CalendarEvent
+from tests.helpers.sqlite_db import make_temp_sqlite
 
-_TMPDB = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
+_TS, _ENGINE, _TMPDB = make_temp_sqlite(cdb.Base.metadata)
-_ENGINE = create_engine(
-    f"sqlite:///{_TMPDB.name}",
-    connect_args={"check_same_thread": False},
-    poolclass=NullPool,
-)
-cdb.Base.metadata.create_all(_ENGINE)
-_TS = sessionmaker(bind=_ENGINE, autoflush=False, autocommit=False)
 
 
 @pytest.fixture(autouse=True)

tests/test_replace_messages_multimodal.py

@@ -10,26 +10,16 @@ back as a corrupted string blob - the attachment was destroyed. The
 sibling _persist_message json.dumps-es list content; replace_messages did
 not.
 """
-import tempfile
 import uuid
 
 import pytest
-from sqlalchemy import create_engine
-from sqlalchemy.orm import sessionmaker
-from sqlalchemy.pool import NullPool
 
 import core.database as cdb
 from core.database import Session as DbSession
 from core.models import ChatMessage
+from tests.helpers.sqlite_db import make_temp_sqlite
 
-_TMPDB = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
+_TS, _ENGINE, _TMPDB = make_temp_sqlite(cdb.Base.metadata)
-_ENGINE = create_engine(
-    f"sqlite:///{_TMPDB.name}",
-    connect_args={"check_same_thread": False},
-    poolclass=NullPool,
-)
-cdb.Base.metadata.create_all(_ENGINE)
-_TS = sessionmaker(bind=_ENGINE, autoflush=False, autocommit=False)
 
 
 @pytest.fixture