Fix Matter light get brightness (home-assistant#149186)

Author: jvmahon

homeassistant/components/matter/light.py

@@ -5,6 +5,7 @@
 from typing import Any
 
 from chip.clusters import Objects as clusters
+from chip.clusters.Objects import NullValue
 from matter_server.client.models import device_types
 
 from homeassistant.components.light import (
@@ -241,7 +242,7 @@ def _get_color_temperature(self) -> int:
 
         return int(color_temp)
 
-    def _get_brightness(self) -> int:
+    def _get_brightness(self) -> int | None:
         """Get brightness from matter."""
 
         level_control = self._endpoint.get_cluster(clusters.LevelControl)
@@ -255,6 +256,10 @@ def _get_brightness(self) -> int:
             self.entity_id,
         )
 
+        if level_control.currentLevel is NullValue:
+            # currentLevel is a nullable value.
+            return None
+
         return round(
             renormalize(
                 level_control.currentLevel,

tests/components/matter/test_light.py

@@ -131,6 +131,15 @@ async def test_dimmable_light(
 ) -> None:
     """Test a dimmable light."""
 
+    # Test for currentLevel is None
+    set_node_attribute(matter_node, 1, 8, 0, None)
+    await trigger_subscription_callback(hass, matter_client)
+
+    state = hass.states.get(entity_id)
+    assert state is not None
+    assert state.state == "on"
+    assert state.attributes["brightness"] is None
+
     # Test that the light brightness is 50 (out of 254)
     set_node_attribute(matter_node, 1, 8, 0, 50)
     await trigger_subscription_callback(hass, matter_client)