"""Test DagFileProcessorManager._fetch_callbacks method"""
        dag_filepath = TEST_DAG_FOLDER / "test_on_failure_callback_dag.py"
        callback1 = DagCallbackRequest(
            dag_id="test_start_date_scheduling",
            full_filepath=str(dag_filepath),
            is_failure_callback=True,
            processor_subdir=str(tmpdir),
            run_id="123",
        )
        callback2 = DagCallbackRequest(
            dag_id="test_start_date_scheduling",
            full_filepath=str(dag_filepath),
            is_failure_callback=True,
            processor_subdir=str(tmpdir),
            run_id="456",
        )
        callback3 = SlaCallbackRequest(
            dag_id="test_start_date_scheduling",
            full_filepath=str(dag_filepath),
            processor_subdir=str(tmpdir),
        )
        with create_session() as session:
            session.add(DbCallbackRequest(callback=callback1, priority_weight=11))
            session.add(DbCallbackRequest(callback=callback2, priority_weight=10))
            session.add(DbCallbackRequest(callback=callback3, priority_weight=9))
        child_pipe, parent_pipe = multiprocessing.Pipe()
        manager = DagFileProcessorManager(
            dag_directory=str(tmpdir),
            max_runs=1,
            processor_timeout=timedelta(days=365),