add more tests for weird timezone/DST boundaries in schedules

see: https://github.com/ansible/awx/pull/1024

awx/api/views.py

@@ -619,7 +619,19 @@ class SchedulePreview(GenericAPIView):
     def post(self, request):
         serializer = self.get_serializer(data=request.data)
         if serializer.is_valid():
-            schedule = list(Schedule.rrulestr(serializer.validated_data['rrule']).xafter(now(), count=10))
+            next_stamp = now()
+            schedule = []
+            gen = Schedule.rrulestr(serializer.validated_data['rrule']).xafter(next_stamp, count=20)
+
+            # loop across the entire generator and grab the first 10 events
+            for event in gen:
+                if len(schedule) >= 10:
+                    break
+                if not dateutil.tz.datetime_exists(event):
+                    # skip imaginary dates, like 2:30 on DST boundaries
+                    continue
+                schedule.append(event)
+
             return Response({
                 'local': schedule,
                 'utc': [s.astimezone(pytz.utc) for s in schedule]

awx/main/models/schedules.py

@@ -5,7 +5,7 @@ import re
 import logging
 import datetime
 import dateutil.rrule
-from dateutil.tz import gettz
+from dateutil.tz import gettz, datetime_exists
 
 # Django
 from django.db import models
@@ -185,7 +185,11 @@ class Schedule(CommonModel, LaunchTimeConfig):
     def update_computed_fields(self):
         future_rs = Schedule.rrulestr(self.rrule, forceset=True)
         next_run_actual = future_rs.after(now())
+
         if next_run_actual is not None:
+            if not datetime_exists(next_run_actual):
+                # skip imaginary dates, like 2:30 on DST boundaries
+                next_run_actual = future_rs.after(next_run_actual)
             next_run_actual = next_run_actual.astimezone(pytz.utc)
 
         self.next_run = next_run_actual

awx/main/tests/functional/api/test_schedules.py

@@ -158,3 +158,118 @@ def test_interval_by_local_day(post, admin_user):
         '2030-04-07 01:00:00+00:00',
         '2030-05-05 01:00:00+00:00',
     ]
+
+
+@pytest.mark.django_db
+def test_weekday_timezone_boundary(post, admin_user):
+    url = reverse('api:schedule_rrule')
+    rrule = 'DTSTART;TZID=America/New_York:20300101T210000 RRULE:FREQ=WEEKLY;BYDAY=TU;INTERVAL=1;COUNT=3'
+    r = post(url, {'rrule': rrule}, admin_user, expect=200)
+
+    assert map(str, r.data['local']) == [
+        '2030-01-01 21:00:00-05:00',
+        '2030-01-08 21:00:00-05:00',
+        '2030-01-15 21:00:00-05:00',
+    ]
+
+    assert map(str, r.data['utc']) == [
+        '2030-01-02 02:00:00+00:00',
+        '2030-01-09 02:00:00+00:00',
+        '2030-01-16 02:00:00+00:00',
+    ]
+
+
+@pytest.mark.django_db
+def test_first_monthly_weekday_timezone_boundary(post, admin_user):
+    url = reverse('api:schedule_rrule')
+    rrule = 'DTSTART;TZID=America/New_York:20300101T210000 RRULE:FREQ=MONTHLY;BYDAY=SU;BYSETPOS=1;INTERVAL=1;COUNT=3'
+    r = post(url, {'rrule': rrule}, admin_user, expect=200)
+
+    assert map(str, r.data['local']) == [
+        '2030-01-06 21:00:00-05:00',
+        '2030-02-03 21:00:00-05:00',
+        '2030-03-03 21:00:00-05:00',
+    ]
+
+    assert map(str, r.data['utc']) == [
+        '2030-01-07 02:00:00+00:00',
+        '2030-02-04 02:00:00+00:00',
+        '2030-03-04 02:00:00+00:00',
+    ]
+
+
+@pytest.mark.django_db
+def test_annual_timezone_boundary(post, admin_user):
+    url = reverse('api:schedule_rrule')
+    rrule = 'DTSTART;TZID=America/New_York:20301231T230000 RRULE:FREQ=YEARLY;INTERVAL=1;COUNT=3'
+    r = post(url, {'rrule': rrule}, admin_user, expect=200)
+
+    assert map(str, r.data['local']) == [
+        '2030-12-31 23:00:00-05:00',
+        '2031-12-31 23:00:00-05:00',
+        '2032-12-31 23:00:00-05:00',
+    ]
+
+    assert map(str, r.data['utc']) == [
+        '2031-01-01 04:00:00+00:00',
+        '2032-01-01 04:00:00+00:00',
+        '2033-01-01 04:00:00+00:00',
+    ]
+
+
+def test_dst_phantom_hour(post, admin_user):
+    # The DST period in the United States begins at 02:00 (2 am) local time, so
+    # the hour from 2:00:00 to 2:59:59 does not exist in the night of the
+    # switch.
+
+    # Three Sundays, starting 2:30AM America/New_York, starting Mar 3, 2030,
+    # should _not_ include Mar 10, 2030 @ 2:30AM (because it doesn't exist)
+    url = reverse('api:schedule_rrule')
+    rrule = 'DTSTART;TZID=America/New_York:20300303T023000 RRULE:FREQ=WEEKLY;BYDAY=SU;INTERVAL=1;COUNT=3'
+    r = post(url, {'rrule': rrule}, admin_user, expect=200)
+
+    assert map(str, r.data['local']) == [
+        '2030-03-03 02:30:00-05:00',
+        '2030-03-17 02:30:00-04:00',  # Skip 3/10 because 3/10 @ 2:30AM isn't a real date
+    ]
+
+    assert map(str, r.data['utc']) == [
+        '2030-03-03 07:30:00+00:00',
+        '2030-03-17 06:30:00+00:00',  # Skip 3/10 because 3/10 @ 2:30AM isn't a real date
+    ]
+
+
+@pytest.mark.django_db
+def test_months_with_31_days(post, admin_user):
+    url = reverse('api:schedule_rrule')
+    rrule = 'DTSTART;TZID=America/New_York:20300101T000000 RRULE:FREQ=MONTHLY;INTERVAL=1;BYMONTHDAY=31;COUNT=7'
+    r = post(url, {'rrule': rrule}, admin_user, expect=200)
+
+    # 30 days have September, April, June, and November...
+    assert map(str, r.data['local']) == [
+        '2030-01-31 00:00:00-05:00',
+        '2030-03-31 00:00:00-04:00',
+        '2030-05-31 00:00:00-04:00',
+        '2030-07-31 00:00:00-04:00',
+        '2030-08-31 00:00:00-04:00',
+        '2030-10-31 00:00:00-04:00',
+        '2030-12-31 00:00:00-05:00',
+    ]
+
+
+def test_dst_rollback_duplicates(post, admin_user):
+    # From Nov 2 -> Nov 3, 2030, daylight savings ends and we "roll back" an hour.
+    # Make sure we don't "double count" duplicate times in the "rolled back"
+    # hour.
+
+    url = reverse('api:schedule_rrule')
+    rrule = 'DTSTART;TZID=America/New_York:20301102T233000 RRULE:FREQ=HOURLY;INTERVAL=1;COUNT=5'
+    r = post(url, {'rrule': rrule}, admin_user, expect=200)
+
+    assert map(str, r.data['local']) == [
+        '2030-11-02 23:30:00-04:00',
+        '2030-11-03 00:30:00-04:00',
+        '2030-11-03 01:30:00-04:00',
+        '2030-11-03 02:30:00-05:00',
+        '2030-11-03 03:30:00-05:00',
+    ]

awx/main/tests/functional/models/test_schedule.py

@@ -1,5 +1,10 @@
-from awx.main.models import JobTemplate, Schedule
+from datetime import datetime
+
+import mock
 import pytest
+import pytz
+
+from awx.main.models import JobTemplate, Schedule
 
 
 @pytest.fixture
@@ -166,3 +171,24 @@ def test_utc_until_in_the_past(job_template):
     s.save()
 
     assert s.next_run is s.dtstart is s.dtend is None
+
+
+@pytest.mark.django_db
+@mock.patch('awx.main.models.schedules.now', lambda: datetime(2030, 03, 05, tzinfo=pytz.utc))
+def test_dst_phantom_hour(job_template):
+    # The DST period in the United States begins at 02:00 (2 am) local time, so
+    # the hour from 2:00:00 to 2:59:59 does not exist in the night of the
+    # switch.
+
+    # Three Sundays, starting 2:30AM America/New_York, starting Mar 3, 2030,
+    # (which doesn't exist)
+    rrule = 'DTSTART;TZID=America/New_York:20300303T023000 RRULE:FREQ=WEEKLY;BYDAY=SU;INTERVAL=1;COUNT=3'
+    s = Schedule(
+        name='Some Schedule',
+        rrule=rrule,
+        unified_job_template=job_template
+    )
+    s.save()
+
+    # 3/10/30 @ 2:30AM is skipped because it _doesn't exist_ <cue twilight zone music>
+    assert str(s.next_run) == '2030-03-17 06:30:00+00:00'