Update brightness optimistically when turning on a dimmable light (#178505)

Signed-off-by: Stephan Peijnik-Steinwender <speijnik@gmail.com>

homeassistant/components/netatmo/light.py

@@ -183,6 +183,7 @@ class NetatmoLight(NetatmoReachabilityEntity, LightEntity):
             await self.device.async_set_brightness(
                 round(kwargs[ATTR_BRIGHTNESS] / 2.55)
             )
+            self._attr_brightness = kwargs[ATTR_BRIGHTNESS]
 
         else:
             await self.device.async_on()

tests/components/netatmo/test_light.py

@@ -211,3 +211,44 @@ async def test_light_setup_and_services(
                 ]
             }
         )
+
+
+async def test_dimmable_light_turn_on_updates_brightness_optimistically(
+    hass: HomeAssistant, config_entry: MockConfigEntry, netatmo_auth: AsyncMock
+) -> None:
+    """Test that turning on a dimmable light with a brightness updates state immediately.
+
+    The Netatmo API doesn't push brightness changes back until the next poll,
+    which can be several minutes away, so the new brightness must be reflected
+    optimistically instead of waiting for that poll.
+    """
+    with selected_platforms(["light"]):
+        assert await hass.config_entries.async_setup(config_entry.entry_id)
+
+        await hass.async_block_till_done()
+
+    light_entity = "light.unknown_00_11_22_33_00_11_45_fe"
+
+    with patch("pyatmo.home.Home.async_set_state") as mock_set_state:
+        await hass.services.async_call(
+            LIGHT_DOMAIN,
+            SERVICE_TURN_ON,
+            {ATTR_ENTITY_ID: light_entity, "brightness": 128},
+            blocking=True,
+        )
+        await hass.async_block_till_done()
+        mock_set_state.assert_called_once_with(
+            {
+                "modules": [
+                    {
+                        "id": "00:11:22:33:00:11:45:fe",
+                        "brightness": round(128 / 2.55),
+                        "bridge": "12:34:56:80:60:40",
+                    }
+                ]
+            }
+        )
+
+    state = hass.states.get(light_entity)
+    assert state.state == "on"
+    assert state.attributes["brightness"] == 128