Refactor _is_valid_suggested_unit in sensor (#151956)

homeassistant/components/sensor/__init__.py

@@ -361,25 +361,30 @@ class SensorEntity(Entity, cached_properties=CACHED_PROPERTIES_WITH_ATTR_):
     def _is_valid_suggested_unit(self, suggested_unit_of_measurement: str) -> bool:
         """Validate the suggested unit.
 
-        Validate that a unit converter exists for the sensor's device class and that the
-        unit converter supports both the native and the suggested units of measurement.
+        Validate that the native unit of measurement can be converted to the
+        suggested unit of measurement, either because they are the same or
+        because a unit converter supports both.
         """
-        # Make sure we can convert the units
-        if self.native_unit_of_measurement != suggested_unit_of_measurement and (
-            (unit_converter := UNIT_CONVERTERS.get(self.device_class)) is None
-            or self.__native_unit_of_measurement_compat
-            not in unit_converter.VALID_UNITS
-            or suggested_unit_of_measurement not in unit_converter.VALID_UNITS
-        ):
-            if not self._invalid_suggested_unit_of_measurement_reported:
-                self._invalid_suggested_unit_of_measurement_reported = True
-                raise ValueError(
-                    f"Entity {type(self)} suggest an incorrect "
-                    f"unit of measurement: {suggested_unit_of_measurement}."
-                )
-            return False
+        # No need to check the unit converter if the units are the same
+        if self.native_unit_of_measurement == suggested_unit_of_measurement:
+            return True
 
-        return True
+        # Make sure there is a unit converter and it supports both units
+        if (
+            (unit_converter := UNIT_CONVERTERS.get(self.device_class))
+            and self.__native_unit_of_measurement_compat in unit_converter.VALID_UNITS
+            and suggested_unit_of_measurement in unit_converter.VALID_UNITS
+        ):
+            return True
+
+        # Report invalid suggested unit only once per entity
+        if not self._invalid_suggested_unit_of_measurement_reported:
+            self._invalid_suggested_unit_of_measurement_reported = True
+            raise ValueError(
+                f"Entity {type(self)} suggest an incorrect "
+                f"unit of measurement: {suggested_unit_of_measurement}."
+            )
+        return False
 
     def _get_initial_suggested_unit(self) -> str | UndefinedType:
         """Return the initial unit."""