Fix mqtt json light state updates using deprecated color handling

homeassistant/components/mqtt/light/schema_json.py

@@ -406,6 +406,9 @@ def state_received(msg: ReceiveMessage) -> None:
                         values["color_temp"],
                         self.entity_id,
                     )
+                # Allow to switch back to color_temp
+                if "color" not in values:
+                    self._attr_hs_color = None
 
             if self.supported_features and LightEntityFeature.EFFECT:
                 with suppress(KeyError):

tests/components/mqtt/test_light_json.py

@@ -725,6 +725,93 @@ async def test_controlling_state_via_topic2(
     )
 
 
+@pytest.mark.parametrize(
+    "hass_config",
+    [
+        {
+            mqtt.DOMAIN: {
+                light.DOMAIN: {
+                    "schema": "json",
+                    "name": "test",
+                    "command_topic": "test_light_rgb/set",
+                    "state_topic": "test_light_rgb/set",
+                    "rgb": True,
+                    "color_temp": True,
+                    "brightness": True,
+                }
+            }
+        }
+    ],
+)
+async def test_controlling_the_state_with_legacy_color_handling(
+    hass: HomeAssistant, mqtt_mock_entry: MqttMockHAClientGenerator
+) -> None:
+    """Test state updates for lights with a legacy color handling."""
+    supported_color_modes = ["color_temp", "hs"]
+    await mqtt_mock_entry()
+
+    state = hass.states.get("light.test")
+    assert state.state == STATE_UNKNOWN
+    expected_features = light.SUPPORT_FLASH | light.SUPPORT_TRANSITION
+    assert state.attributes.get(ATTR_SUPPORTED_FEATURES) == expected_features
+    assert state.attributes.get("brightness") is None
+    assert state.attributes.get("color_mode") is None
+    assert state.attributes.get("color_temp") is None
+    assert state.attributes.get("effect") is None
+    assert state.attributes.get("hs_color") is None
+    assert state.attributes.get("rgb_color") is None
+    assert state.attributes.get("rgbw_color") is None
+    assert state.attributes.get("rgbww_color") is None
+    assert state.attributes.get("supported_color_modes") == supported_color_modes
+    assert state.attributes.get("xy_color") is None
+    assert not state.attributes.get(ATTR_ASSUMED_STATE)
+
+    for _ in range(0, 2):
+        # Returned state after the light was turned on
+        # Receiving legacy color mode: rgb.
+        async_fire_mqtt_message(
+            hass,
+            "test_light_rgb/set",
+            '{ "state": "ON", "brightness": 255, "level": 100, "hue": 16,'
+            '"saturation": 100, "color": { "r": 255, "g": 67, "b": 0 }, '
+            '"bulb_mode": "color", "color_mode": "rgb" }',
+        )
+
+        state = hass.states.get("light.test")
+        assert state.state == STATE_ON
+        assert state.attributes.get("brightness") == 255
+        assert state.attributes.get("color_mode") == "hs"
+        assert state.attributes.get("color_temp") is None
+        assert state.attributes.get("effect") is None
+        assert state.attributes.get("hs_color") == (15.765, 100.0)
+        assert state.attributes.get("rgb_color") == (255, 67, 0)
+        assert state.attributes.get("rgbw_color") is None
+        assert state.attributes.get("rgbww_color") is None
+        assert state.attributes.get("xy_color") == (0.674, 0.322)
+
+        # Returned state after the lights color mode was changed
+        # Receiving legacy color mode: color_temp
+        async_fire_mqtt_message(
+            hass,
+            "test_light_rgb/set",
+            '{ "state": "ON", "brightness": 255, "level": 100, '
+            '"kelvin": 92, "color_temp": 353, "bulb_mode": "white", '
+            '"color_mode": "color_temp" }',
+        )
+
+        state = hass.states.get("light.test")
+        assert state.state == STATE_ON
+        assert state.attributes.get("brightness") == 255
+        assert state.attributes.get("color_mode") == "color_temp"
+        assert state.attributes.get("color_temp") == 353
+        assert state.attributes.get("effect") is None
+        assert state.attributes.get("hs_color") == (28.125, 61.661)
+        assert state.attributes.get("rgb_color") == (255, 171, 97)
+        assert state.attributes.get("rgbw_color") is None
+        assert state.attributes.get("rgbww_color") is None
+        assert state.attributes.get("xy_color") == (0.513, 0.386)
+
+
 @pytest.mark.parametrize(
     "hass_config",
     [