We have flaky scheduler test:


https://github.com/apache/airflow/pull/11659/checks?check_run_id=1279791496#step:6:527


_______________ TestSchedulerJob.test_scheduler_task_start_date ________________

self = <tests.jobs.test_scheduler_job.TestSchedulerJob testMethod=test_scheduler_task_start_date>

    def test_scheduler_task_start_date(self):
        """
        Test that the scheduler respects task start dates that are different from DAG start dates
        """
    
        dagbag = DagBag(dag_folder=os.path.join(settings.DAGS_FOLDER, "no_dags.py"), include_examples=False)
        dag_id = 'test_task_start_date_scheduling'
        dag = self.dagbag.get_dag(dag_id)
        dag.is_paused_upon_creation = False
        dagbag.bag_dag(dag=dag, root_dag=dag)
    
        # Deactivate other dags in this file so the scheduler doesn't waste time processing them
        other_dag = self.dagbag.get_dag('test_start_date_scheduling')
        other_dag.is_paused_upon_creation = True
        dagbag.bag_dag(dag=other_dag, root_dag=other_dag)
    
        dagbag.sync_to_db()
    
        scheduler = SchedulerJob(executor=self.null_exec,
                                 subdir=dag.fileloc,
                                 num_runs=2)
        scheduler.run()
    
        session = settings.Session()
        tiq = session.query(TaskInstance).filter(TaskInstance.dag_id == dag_id)
        ti1s = tiq.filter(TaskInstance.task_id == 'dummy1').all()
        ti2s = tiq.filter(TaskInstance.task_id == 'dummy2').all()
        self.assertEqual(len(ti1s), 0)
>       self.assertEqual(len(ti2s), 2)
E       AssertionError: 1 != 2
tests/models/test_taskinstance.py
with DAG(dag_id='test_dag'):
            task = DummyOperator(task_id='task', start_date=DEFAULT_DATE)
            downstream_task = DummyOperator(task_id='downstream_task', start_date=DEFAULT_DATE)
            task >> downstream_task
        ti = TI(task, DEFAULT_DATE)
        downstream_ti = TI(downstream_task, DEFAULT_DATE)
        downstream_ti.set_state(downstream_ti_state)
        assert ti.are_dependents_done() == expected_are_dependents_done
    def test_xcom_pull(self):
        """
        Test xcom_pull, using different filtering methods.
        """
        dag = models.DAG(
            dag_id='test_xcom',
            schedule_interval='@monthly',
            start_date=timezone.datetime(2016, 6, 1, 0, 0, 0),
        )
        exec_date = timezone.utcnow()
        
        task1 = DummyOperator(task_id='test_xcom_1', dag=dag, owner='airflow')
        ti1 = TI(task=task1, execution_date=exec_date)