Always update Filter sensors attr on new_state (#89096)

* always update attr

* reset filter on unit change

homeassistant/components/filter/sensor.py

@@ -18,10 +18,8 @@ from homeassistant.components.input_number import DOMAIN as INPUT_NUMBER_DOMAIN
 from homeassistant.components.recorder import get_instance, history
 from homeassistant.components.sensor import (
     ATTR_STATE_CLASS,
-    DEVICE_CLASSES as SENSOR_DEVICE_CLASSES,
     DOMAIN as SENSOR_DOMAIN,
     PLATFORM_SCHEMA,
-    STATE_CLASSES as SENSOR_STATE_CLASSES,
     SensorDeviceClass,
     SensorEntity,
 )
@@ -273,22 +271,15 @@ class SensorFilter(SensorEntity):
 
         self._state = temp_state.state
 
-        if self._attr_icon is None:
-            self._attr_icon = new_state.attributes.get(ATTR_ICON, ICON)
+        self._attr_icon = new_state.attributes.get(ATTR_ICON, ICON)
+        self._attr_device_class = new_state.attributes.get(ATTR_DEVICE_CLASS)
+        self._attr_state_class = new_state.attributes.get(ATTR_STATE_CLASS)
 
-        if (
-            self._attr_device_class is None
-            and new_state.attributes.get(ATTR_DEVICE_CLASS) in SENSOR_DEVICE_CLASSES
+        if self._attr_native_unit_of_measurement != new_state.attributes.get(
+            ATTR_UNIT_OF_MEASUREMENT
         ):
-            self._attr_device_class = new_state.attributes.get(ATTR_DEVICE_CLASS)
-
-        if (
-            self._attr_state_class is None
-            and new_state.attributes.get(ATTR_STATE_CLASS) in SENSOR_STATE_CLASSES
-        ):
-            self._attr_state_class = new_state.attributes.get(ATTR_STATE_CLASS)
-
-        if self._attr_native_unit_of_measurement is None:
+            for filt in self._filters:
+                filt.reset()
             self._attr_native_unit_of_measurement = new_state.attributes.get(
                 ATTR_UNIT_OF_MEASUREMENT
             )
@@ -460,6 +451,10 @@ class Filter:
         """Return whether the current filter_state should be skipped."""
         return self._skip_processing
 
+    def reset(self) -> None:
+        """Reset filter."""
+        self.states.clear()
+
     def _filter_state(self, new_state: FilterState) -> FilterState:
         """Implement filter."""
         raise NotImplementedError()