Correct min/max mireds for lights which use K for color temp (#79998)

homeassistant/components/light/__init__.py

@@ -911,11 +911,20 @@ class LightEntity(ToggleEntity):
         supported_color_modes = self._light_internal_supported_color_modes
 
         if ColorMode.COLOR_TEMP in supported_color_modes:
-            data[ATTR_MIN_MIREDS] = self.min_mireds
-            data[ATTR_MAX_MIREDS] = self.max_mireds
             data[ATTR_MIN_COLOR_TEMP_KELVIN] = self.min_color_temp_kelvin
             data[ATTR_MAX_COLOR_TEMP_KELVIN] = self.max_color_temp_kelvin
-
+            if not self.max_color_temp_kelvin:
+                data[ATTR_MIN_MIREDS] = None
+            else:
+                data[ATTR_MIN_MIREDS] = color_util.color_temperature_kelvin_to_mired(
+                    self.max_color_temp_kelvin
+                )
+            if not self.min_color_temp_kelvin:
+                data[ATTR_MAX_MIREDS] = None
+            else:
+                data[ATTR_MAX_MIREDS] = color_util.color_temperature_kelvin_to_mired(
+                    self.min_color_temp_kelvin
+                )
         if supported_features & LightEntityFeature.EFFECT:
             data[ATTR_EFFECT_LIST] = self.effect_list
 

tests/components/group/test_light.py

@@ -821,13 +821,13 @@ async def test_min_max_mireds(hass, enable_custom_integrations):
     entity0.supported_color_modes = {ColorMode.COLOR_TEMP}
     entity0.color_mode = ColorMode.COLOR_TEMP
     entity0.color_temp_kelvin = 2
-    entity0.min_color_temp_kelvin = 2
+    entity0._attr_min_color_temp_kelvin = 2
-    entity0.max_color_temp_kelvin = 5
+    entity0._attr_max_color_temp_kelvin = 5
 
     entity1 = platform.ENTITIES[1]
     entity1.supported_features = SUPPORT_COLOR_TEMP
-    entity1.min_color_temp_kelvin = 1
+    entity1._attr_min_color_temp_kelvin = 1
-    entity1.max_color_temp_kelvin = 1234567890
+    entity1._attr_max_color_temp_kelvin = 1234567890
 
     assert await async_setup_component(
         hass,

tests/components/light/test_init.py

@@ -1903,6 +1903,10 @@ async def test_light_service_call_color_temp_conversion(
         light.ColorMode.COLOR_TEMP,
         light.ColorMode.RGBWW,
     ]
+    assert state.attributes["min_mireds"] == 153
+    assert state.attributes["max_mireds"] == 500
+    assert state.attributes["min_color_temp_kelvin"] == 2000
+    assert state.attributes["max_color_temp_kelvin"] == 6500
 
     state = hass.states.get(entity1.entity_id)
     assert state.attributes["supported_color_modes"] == [light.ColorMode.RGBWW]
@@ -2001,6 +2005,52 @@ async def test_light_service_call_color_temp_conversion(
     assert data == {"brightness": 255, "rgbww_color": (0, 0, 0, 66, 189)}
 
 
+async def test_light_mired_color_temp_conversion(hass, enable_custom_integrations):
+    """Test color temp conversion from K to legacy mired."""
+    platform = getattr(hass.components, "test.light")
+    platform.init(empty=True)
+
+    platform.ENTITIES.append(platform.MockLight("Test_rgbww_ct", STATE_ON))
+    platform.ENTITIES.append(platform.MockLight("Test_rgbww", STATE_ON))
+
+    entity0 = platform.ENTITIES[0]
+    entity0.supported_color_modes = {
+        light.ColorMode.COLOR_TEMP,
+    }
+    entity0._attr_min_color_temp_kelvin = 1800
+    entity0._attr_max_color_temp_kelvin = 6700
+
+    assert await async_setup_component(hass, "light", {"light": {"platform": "test"}})
+    await hass.async_block_till_done()
+
+    state = hass.states.get(entity0.entity_id)
+    assert state.attributes["supported_color_modes"] == [light.ColorMode.COLOR_TEMP]
+    assert state.attributes["min_mireds"] == 149
+    assert state.attributes["max_mireds"] == 555
+    assert state.attributes["min_color_temp_kelvin"] == 1800
+    assert state.attributes["max_color_temp_kelvin"] == 6700
+
+    await hass.services.async_call(
+        "light",
+        "turn_on",
+        {
+            "entity_id": [
+                entity0.entity_id,
+            ],
+            "brightness_pct": 100,
+            "color_temp_kelvin": 3500,
+        },
+        blocking=True,
+    )
+    _, data = entity0.last_call("turn_on")
+    assert data == {"brightness": 255, "color_temp": 285, "color_temp_kelvin": 3500}
+
+    state = hass.states.get(entity0.entity_id)
+    assert state.attributes["color_mode"] == light.ColorMode.COLOR_TEMP
+    assert state.attributes["color_temp"] == 285
+    assert state.attributes["color_temp_kelvin"] == 3500
+
+
 async def test_light_service_call_white_mode(hass, enable_custom_integrations):
     """Test color_mode white in service calls."""
     platform = getattr(hass.components, "test.light")

tests/testing_config/custom_components/test/light.py

@@ -37,8 +37,8 @@ class MockLight(MockToggleEntity, LightEntity):
     """Mock light class."""
 
     color_mode = None
-    max_color_temp_kelvin = 6500
+    _attr_max_color_temp_kelvin = 6500
-    min_color_temp_kelvin = 2000
+    _attr_min_color_temp_kelvin = 2000
     supported_color_modes = None
     supported_features = 0