Fixed AndTrigger skipping run times (#914)

Removed redundant `self._next_triggers` construction and added `AndTrigger` test.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Alex Grönholm <[email protected]>

docs/versionhistory.rst

@@ -30,6 +30,8 @@ APScheduler, see the :doc:`migration section <migration>`.
   (PR by MohammadAmin Vahedinia)
 - Fixed the shutdown procedure of the Redis event broker
 - Fixed ``SQLAlchemyDataStore`` not respecting custom schema name when creating enums
+- Fixed skipped intervals with overlapping schedules in ``AndTrigger``
+  (#911 <https://github.com/agronholm/apscheduler/issues/911>_; PR by Bennett Meares)
 
 **4.0.0a4**
 

src/apscheduler/triggers/combining.py

@@ -87,7 +87,6 @@ def next(self) -> datetime | None:
 
             # If all the fire times were within the threshold, return the earliest one
             if latest_fire_time - earliest_fire_time <= self.threshold:
-                self._next_fire_times = [t.next() for t in self.triggers]
                 return earliest_fire_time
         else:
             raise MaxIterationsReached

tests/triggers/test_combining.py

@@ -1,11 +1,13 @@
 from __future__ import annotations
 
-from datetime import datetime, timedelta
+from datetime import datetime, timedelta, timezone
 
 import pytest
 
 from apscheduler import MaxIterationsReached
+from apscheduler.triggers.calendarinterval import CalendarIntervalTrigger
 from apscheduler.triggers.combining import AndTrigger, OrTrigger
+from apscheduler.triggers.cron import CronTrigger
 from apscheduler.triggers.date import DateTrigger
 from apscheduler.triggers.interval import IntervalTrigger
 
@@ -62,6 +64,103 @@ def test_repr(self, timezone, serializer):
             "threshold=1.0, max_iterations=10000)"
         )
 
+    @pytest.mark.parametrize(
+        "left_trigger,right_trigger,expected_datetimes",
+        [
+            (
+                IntervalTrigger(
+                    hours=6, start_time=datetime(2024, 5, 1, tzinfo=timezone.utc)
+                ),
+                IntervalTrigger(
+                    hours=12, start_time=datetime(2024, 5, 1, tzinfo=timezone.utc)
+                ),
+                [
+                    datetime(2024, 5, 1, 0, tzinfo=timezone.utc),
+                    datetime(2024, 5, 1, 12, tzinfo=timezone.utc),
+                    datetime(2024, 5, 2, 0, tzinfo=timezone.utc),
+                ],
+            ),
+            (
+                IntervalTrigger(
+                    days=1, start_time=datetime(2024, 5, 1, tzinfo=timezone.utc)
+                ),
+                IntervalTrigger(
+                    weeks=1, start_time=datetime(2024, 5, 1, tzinfo=timezone.utc)
+                ),
+                [
+                    datetime(2024, 5, 1, tzinfo=timezone.utc),
+                    datetime(2024, 5, 8, tzinfo=timezone.utc),
+                    datetime(2024, 5, 15, tzinfo=timezone.utc),
+                ],
+            ),
+            (
+                CronTrigger(
+                    day_of_week="mon-fri",
+                    hour="*",
+                    timezone=timezone.utc,
+                    start_time=datetime(2024, 5, 3, tzinfo=timezone.utc),
+                ),
+                IntervalTrigger(
+                    hours=12, start_time=datetime(2024, 5, 3, tzinfo=timezone.utc)
+                ),
+                [
+                    datetime(2024, 5, 3, 0, tzinfo=timezone.utc),
+                    datetime(2024, 5, 3, 12, tzinfo=timezone.utc),
+                    datetime(2024, 5, 6, 0, tzinfo=timezone.utc),
+                ],
+            ),
+            (
+                CronTrigger(
+                    day_of_week="mon-fri",
+                    timezone=timezone.utc,
+                    start_time=datetime(2024, 5, 13, tzinfo=timezone.utc),
+                ),
+                IntervalTrigger(
+                    days=4, start_time=datetime(2024, 5, 13, tzinfo=timezone.utc)
+                ),
+                [
+                    datetime(2024, 5, 13, tzinfo=timezone.utc),
+                    datetime(2024, 5, 17, tzinfo=timezone.utc),
+                    datetime(2024, 5, 21, tzinfo=timezone.utc),
+                    datetime(2024, 5, 29, tzinfo=timezone.utc),
+                ],
+            ),
+            (
+                CalendarIntervalTrigger(
+                    months=1,
+                    timezone=timezone.utc,
+                    start_date=datetime(2024, 1, 1, tzinfo=timezone.utc),
+                ),
+                CronTrigger(
+                    day_of_week="mon-fri",
+                    timezone=timezone.utc,
+                    start_time=datetime(2024, 1, 1, tzinfo=timezone.utc),
+                ),
+                [
+                    datetime(2024, 1, 1, tzinfo=timezone.utc),
+                    datetime(2024, 2, 1, tzinfo=timezone.utc),
+                    datetime(2024, 3, 1, tzinfo=timezone.utc),
+                    datetime(2024, 4, 1, tzinfo=timezone.utc),
+                    datetime(2024, 5, 1, tzinfo=timezone.utc),
+                    datetime(2024, 7, 1, tzinfo=timezone.utc),
+                    datetime(2024, 8, 1, tzinfo=timezone.utc),
+                    datetime(2024, 10, 1, tzinfo=timezone.utc),
+                    datetime(2024, 11, 1, tzinfo=timezone.utc),
+                ],
+            ),
+        ],
+    )
+    def test_overlapping_triggers(
+        self, left_trigger, right_trigger, expected_datetimes
+    ):
+        """
+        Verify that the `AndTrigger` fires at the intersection of two triggers.
+        """
+        and_trigger = AndTrigger([left_trigger, right_trigger])
+        for expected_datetime in expected_datetimes:
+            next_datetime = and_trigger.next()
+            assert next_datetime == expected_datetime
+
 
 class TestOrTrigger:
     def test_two_datetriggers(self, timezone, serializer):