Fix boundary case in calednar trigger (#70467)

Update calendar trigger scan logic to add a one second boundary due to the
exclusive search. Add a test that reproduced the issue.

homeassistant/components/calendar/trigger.py

@@ -81,7 +81,8 @@ class CalendarEventListener:
 
     async def _fetch_events(self, last_endtime: datetime.datetime) -> None:
         """Update the set of eligible events."""
-        end_time = last_endtime + UPDATE_INTERVAL
+        # Event time ranges are exclusive so the end time is expanded by 1sec
+        end_time = last_endtime + UPDATE_INTERVAL + datetime.timedelta(seconds=1)
         _LOGGER.debug("Fetching events between %s, %s", last_endtime, end_time)
         events = await self._entity.async_get_events(self._hass, last_endtime, end_time)
 
@@ -125,8 +126,12 @@ class CalendarEventListener:
     async def _handle_calendar_event(self, now: datetime.datetime) -> None:
         """Handle calendar event."""
         _LOGGER.debug("Calendar event @ %s", now)
+        self._dispatch_events(now)
+        self._clear_event_listener()
+        self._listen_next_calendar_event()
 
-        # Consume all events that are eligible to fire
+    def _dispatch_events(self, now: datetime.datetime) -> None:
+        """Dispatch all events that are eligible to fire."""
         while self._events and self._events[0][0] <= now:
             (_fire_time, event) = self._events.pop(0)
             _LOGGER.debug("Event: %s", event)
@@ -134,12 +139,13 @@ class CalendarEventListener:
                 self._job,
                 {"trigger": {**self._trigger_data, "calendar_event": event.as_dict()}},
             )
-        self._clear_event_listener()
-        self._listen_next_calendar_event()
 
     async def _handle_refresh(self, now: datetime.datetime) -> None:
         """Handle core config update."""
         _LOGGER.debug("Refresh events @ %s", now)
+        # Dispatch any eligible events in the boundary case where refresh
+        # fires before the calendar event.
+        self._dispatch_events(now)
         self._clear_event_listener()
         await self._fetch_events(now)
         self._listen_next_calendar_event()

tests/components/calendar/test_trigger.py

@@ -481,3 +481,27 @@ async def test_event_payload(hass, calls, fake_schedule):
             "calendar_event": event_data,
         }
     ]
+
+
+async def test_trigger_timestamp_window_edge(hass, calls, fake_schedule, freezer):
+    """Test that events in the edge of a scan are included."""
+    freezer.move_to("2022-04-19 11:00:00+00:00")
+    # Exactly at a TEST_UPDATE_INTERVAL boundary the start time,
+    # making this excluded from the first window.
+    event_data = fake_schedule.create_event(
+        start=datetime.datetime.fromisoformat("2022-04-19 11:14:00+00:00"),
+        end=datetime.datetime.fromisoformat("2022-04-19 11:30:00+00:00"),
+    )
+    await create_automation(hass, EVENT_START)
+    assert len(calls()) == 0
+
+    await fake_schedule.fire_until(
+        datetime.datetime.fromisoformat("2022-04-19 11:20:00+00:00")
+    )
+    assert calls() == [
+        {
+            "platform": "calendar",
+            "event": EVENT_START,
+            "calendar_event": event_data,
+        }
+    ]