dag = DAG("test_schedule_interval_arg", schedule_interval="*/5 * * * *")
        assert dag.timetable == cron_timetable("*/5 * * * *")
        assert dag.schedule_interval == "*/5 * * * *"
        assert dag.timetable.description == "Every 5 minutes"
    def test_timetable_still_works(self):
        dag = DAG("test_schedule_interval_arg", timetable=cron_timetable("*/6 * * * *"))
        assert dag.timetable == cron_timetable("*/6 * * * *")
        assert dag.schedule_interval == "*/6 * * * *"
        assert dag.timetable.description == "Every 6 minutes"
    @pytest.mark.parametrize(
        "timetable, expected_description",
        [
            (NullTimetable(), "Never, external triggers only"),
            (cron_timetable("0 0 * * *"), "At 00:00"),
            (cron_timetable("@daily"), "At 00:00"),
            (cron_timetable("0 0 * * 0"), "At 00:00, only on Sunday"),
            (cron_timetable("@weekly"), "At 00:00, only on Sunday"),
            (cron_timetable("0 0 1 * *"), "At 00:00, on day 1 of the month"),
            (cron_timetable("@monthly"), "At 00:00, on day 1 of the month"),
            (cron_timetable("0 0 1 */3 *"), "At 00:00, on day 1 of the month, every 3 months"),
            (cron_timetable("@quarterly"), "At 00:00, on day 1 of the month, every 3 months"),
            (cron_timetable("0 0 1 1 *"), "At 00:00, on day 1 of the month, only in January"),
            (cron_timetable("@yearly"), "At 00:00, on day 1 of the month, only in January"),
            (cron_timetable("5 0 * 8 *"), "At 00:05, only in August"),
            (OnceTimetable(), "Once, as soon as possible"),
            (delta_timetable(datetime.timedelta(days=1)), ""),
            (cron_timetable("30 21 * * 5 1"), ""),
        ],
    )
    def test_description_from_timetable(self, timetable, expected_description):