ashb commented on a change in pull request #4117: [AIRFLOW-3277] Correctly
observe DST transitions for cron
URL: https://github.com/apache/incubator-airflow/pull/4117#discussion_r229509804
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File path: tests/models.py
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@@ -580,6 +580,29 @@ def test_cycle(self):
with self.assertRaises(AirflowDagCycleException):
dag.test_cycle()
+ def test_following_previous_schedule(self):
+ """
+ Make sure DST transitions are properly observed
+ """
+ local_tz = pendulum.timezone('Europe/Zurich')
+ start = datetime(2018, 10, 28, 3, 00, tzinfo=local_tz)
+ utc = timezone.convert_to_utc(start)
+
+ dag = DAG('tz_dag', start_date=start, schedule_interval="'*/5 * * *
*'")
+ next = dag.following_schedule(utc)
+ next_local = local_tz.convert(next)
+
+ # should give 2018, 10, 28, 3, 5
+ self.assertEqual(next_local.hour, 3)
+ self.assertEqual(next_local.minute, 5)
+
+ prev = dag.previous_schedule(utc)
+ prev_local = local_tz.convert(prev)
+
+ # should give 2018, 10, 28, 1, 55
+ self.assertEqual(prev_local.hour, 1)
+ self.assertEqual(prev_local.minute, 55)
Review comment:
Tests that cover the 3am case:
```python
start = local_tz.convert(datetime.datetime(2018, 10, 27, 3, 0))
utc = timezone.convert_to_utc(start)
dag = DAG('tz_dag', start_date=start, schedule_interval='0 3 * * *')
next = dag.following_schedule(utc)
next_local = local_tz.convert(next)
self.assertEqual(str(next_local), "2018-10-28 03:00:00+01:00")
self.assertEqual(str(next), "2018-10-28 02:00:00+00:00")
prev = dag.previous_schedule(next)
prev_local = local_tz.convert(prev)
self.assertEqual(str(next_local), "2018-10-27 03:00:00+02:00") #
This fails.
self.assertEqual(str(next), "2018-10-27 01:00:00+00:00")
```
Buuut croniter's get_prev is flaky around DST transition :(
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