diff --git a/fastapi/tests/test_fastapi.py b/fastapi/tests/test_fastapi.py
index 37b11a96..cdec5b18 100644
--- a/fastapi/tests/test_fastapi.py
+++ b/fastapi/tests/test_fastapi.py
@@ -33,6 +33,7 @@ def _mocked_commit(self):
         with unittest.mock.patch.object(
             sql_db.TestCursor, "commit", return_value=None
         ) as mocked_commit:
+            mocked_commit.side_effect = Exception("Commit should not be called")
             yield mocked_commit
 
     def _assert_expected_lang(self, accept_language, expected_lang):