Ensure that this works:

```python
@setup
def mytask():
    print("I am a setup task")

with dag_maker() as dag:
    mytask.override(task_id='newtask')

assert len(dag.task_group.children) == 1
setup_task = dag.task_group.children["newtask"]
assert setup_task._is_setup
```
and teardown also works
"""Create a simple_dag variant that uses timetable instead of schedule_interval."""
    dag = collect_dags(["airflow/example_dags"])["simple_dag"]
    dag.timetable = timetable
    dag.schedule_interval = timetable.summary
    return dag
def serialize_subprocess(queue, dag_folder):
    """Validate pickle in a subprocess."""
    dags = collect_dags(dag_folder)
    for dag in dags.values():
        queue.put(SerializedDAG.to_json(dag))
    queue.put(None)
@pytest.fixture()
def timetable_plugin(monkeypatch):
    """Patch plugins manager to always and only return our custom timetable."""
    from airflow import plugins_manager
    monkeypatch.setattr(plugins_manager, "initialize_timetables_plugins", lambda: None)
    monkeypatch.setattr(
        plugins_manager,
        "timetable_classes",
        {"tests.test_utils.timetables.CustomSerializationTimetable": CustomSerializationTimetable},
    )
class TestStringifiedDAGs:
    """Unit tests for stringified DAGs."""
    def setup_method(self):