Fix utility_meter reset when DST change occurs (#103012)

homeassistant/components/utility_meter/sensor.py

@@ -534,16 +534,25 @@ class UtilityMeterSensor(RestoreSensor):
 
         self.async_write_ha_state()
 
-    async def _async_reset_meter(self, event):
-        """Determine cycle - Helper function for larger than daily cycles."""
+    async def _program_reset(self):
+        """Program the reset of the utility meter."""
         if self._cron_pattern is not None:
+            tz = dt_util.get_time_zone(self.hass.config.time_zone)
             self.async_on_remove(
                 async_track_point_in_time(
                     self.hass,
                     self._async_reset_meter,
-                    croniter(self._cron_pattern, dt_util.now()).get_next(datetime),
+                    croniter(self._cron_pattern, dt_util.now(tz)).get_next(
+                        datetime
+                    ),  # we need timezone for DST purposes (see issue #102984)
                 )
             )
+
+    async def _async_reset_meter(self, event):
+        """Reset the utility meter status."""
+
+        await self._program_reset()
+
         await self.async_reset_meter(self._tariff_entity)
 
     async def async_reset_meter(self, entity_id):
@@ -566,14 +575,7 @@ class UtilityMeterSensor(RestoreSensor):
         """Handle entity which will be added."""
         await super().async_added_to_hass()
 
-        if self._cron_pattern is not None:
-            self.async_on_remove(
-                async_track_point_in_time(
-                    self.hass,
-                    self._async_reset_meter,
-                    croniter(self._cron_pattern, dt_util.now()).get_next(datetime),
-                )
-            )
+        await self._program_reset()
 
         self.async_on_remove(
             async_dispatcher_connect(

tests/components/utility_meter/test_sensor.py

@@ -1266,7 +1266,9 @@ async def _test_self_reset(
     state = hass.states.get("sensor.energy_bill")
     if expect_reset:
         assert state.attributes.get("last_period") == "2"
-        assert state.attributes.get("last_reset") == now.isoformat()
+        assert (
+            state.attributes.get("last_reset") == dt_util.as_utc(now).isoformat()
+        )  # last_reset is kept in UTC
         assert state.state == "3"
     else:
         assert state.attributes.get("last_period") == "0"
@@ -1348,6 +1350,16 @@ async def test_self_reset_hourly(hass: HomeAssistant) -> None:
     )
 
 
+async def test_self_reset_hourly_dst(hass: HomeAssistant) -> None:
+    """Test hourly reset of meter in DST change conditions."""
+
+    hass.config.time_zone = "Europe/Lisbon"
+    dt_util.set_default_time_zone(dt_util.get_time_zone(hass.config.time_zone))
+    await _test_self_reset(
+        hass, gen_config("hourly"), "2023-10-29T01:59:00.000000+00:00"
+    )
+
+
 async def test_self_reset_daily(hass: HomeAssistant) -> None:
     """Test daily reset of meter."""
     await _test_self_reset(