diff --git a/backend/test_group_binding_create_sync.py b/backend/test_group_binding_create_sync.py
index 7d782b9..7d1994f 100644
--- a/backend/test_group_binding_create_sync.py
+++ b/backend/test_group_binding_create_sync.py
@@ -22,7 +22,8 @@ from app.utils.auth import get_current_user
 
 
 @pytest.fixture()
-def db_session():
+def engine():
+    """Create a fresh in-memory database for each test."""
     engine = create_engine(
         "sqlite://",
         connect_args={"check_same_thread": False},
@@ -30,24 +31,43 @@ def db_session():
     )
     from app.models import admin_user, upstream, snapshot, webhook_config, notification_log, custom_page, website, revoked_token, upstream_key
     Base.metadata.create_all(bind=engine)
+    return engine
+
+
+@pytest.fixture()
+def db_session(engine):
+    """Provide a fresh session for the test logic."""
     TestingSessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
     db = TestingSessionLocal()
     try:
         yield db
     finally:
         db.close()
-        Base.metadata.drop_all(bind=engine)
 
 
 @pytest.fixture()
-def client(db_session):
+def client(engine, monkeypatch):
+    """Provide a TestClient with a fresh session factory for each request."""
+    TestingSessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+    
     def override_get_db():
-        yield db_session
+        db = TestingSessionLocal()
+        try:
+            yield db
+        finally:
+            db.close()
+
+    # Mock lifespan-related database initialization to avoid using the real DB file
+    monkeypatch.setattr("app.main.init_db", lambda: None)
+    monkeypatch.setattr("app.main._init_admin", lambda: None)
+    monkeypatch.setattr("app.main.start_scheduler", lambda: None)
+    monkeypatch.setattr("app.main.stop_scheduler", lambda: None)
 
     app.dependency_overrides[get_db] = override_get_db
     app.dependency_overrides[get_current_user] = lambda: object()
     try:
-        yield TestClient(app)
+        with TestClient(app) as c:
+            yield c
     finally:
         app.dependency_overrides.clear()