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
"""
        Tests serialize_operator, make sure the deps is in order
        """
        from airflow.operators.empty import EmptyOperator
        from airflow.sensors.external_task import ExternalTaskSensor
        execution_date = datetime(2020, 1, 1)
        with DAG(dag_id="test_deps_sorted", start_date=execution_date) as dag:
            task1 = ExternalTaskSensor(
                task_id="task1",
                external_dag_id="external_dag_id",
                mode="reschedule",
            )
            task2 = EmptyOperator(task_id="task2")
            task1 >> task2
        serialize_op = SerializedBaseOperator.serialize_operator(dag.task_dict["task1"])
        deps = serialize_op["deps"]
        assert deps == [
            "airflow.ti_deps.deps.not_in_retry_period_dep.NotInRetryPeriodDep",
            "airflow.ti_deps.deps.not_previously_skipped_dep.NotPreviouslySkippedDep",
            "airflow.ti_deps.deps.prev_dagrun_dep.PrevDagrunDep",
            "airflow.ti_deps.deps.ready_to_reschedule.ReadyToRescheduleDep",
            "airflow.ti_deps.deps.trigger_rule_dep.TriggerRuleDep",
        ]
    def test_error_on_unregistered_ti_dep_serialization(self):
        
        class DummyTriggerRule(BaseTIDep):