Stopgap fix for inconsistent upstream API of tplink dimmers (#57285)

homeassistant/components/tplink/light.py

@@ -69,6 +69,14 @@ class TPLinkSmartBulb(CoordinatedTPLinkEntity, LightEntity):
         if (brightness := kwargs.get(ATTR_BRIGHTNESS)) is not None:
             brightness = round((brightness * 100.0) / 255.0)
 
+        if self.device.is_dimmer and transition is None:
+            # This is a stopgap solution for inconsistent set_brightness handling
+            # in the upstream library, see #57265.
+            # This should be removed when the upstream has fixed the issue.
+            # The device logic is to change the settings without turning it on
+            # except when transition is defined, so we leverage that here for now.
+            transition = 1
+
         # Handle turning to temp mode
         if ATTR_COLOR_TEMP in kwargs:
             color_tmp = mired_to_kelvin(int(kwargs[ATTR_COLOR_TEMP]))

tests/components/tplink/__init__.py

@@ -33,6 +33,7 @@ def _mocked_bulb() -> SmartBulb:
     bulb.is_color = True
     bulb.is_strip = False
     bulb.is_plug = False
+    bulb.is_dimmer = False
     bulb.hsv = (10, 30, 5)
     bulb.device_id = MAC_ADDRESS
     bulb.valid_temperature_range.min = 4000

tests/components/tplink/test_light.py

@@ -349,3 +349,29 @@ async def test_off_at_start_light(hass: HomeAssistant) -> None:
     assert state.state == "off"
     attributes = state.attributes
     assert attributes[ATTR_SUPPORTED_COLOR_MODES] == ["onoff"]
+
+
+async def test_dimmer_turn_on_fix(hass: HomeAssistant) -> None:
+    """Test a light."""
+    already_migrated_config_entry = MockConfigEntry(
+        domain=DOMAIN, data={}, unique_id=MAC_ADDRESS
+    )
+    already_migrated_config_entry.add_to_hass(hass)
+    bulb = _mocked_bulb()
+    bulb.is_dimmer = True
+    bulb.is_on = False
+
+    with _patch_discovery(device=bulb), _patch_single_discovery(device=bulb):
+        await async_setup_component(hass, tplink.DOMAIN, {tplink.DOMAIN: {}})
+        await hass.async_block_till_done()
+
+    entity_id = "light.my_bulb"
+
+    state = hass.states.get(entity_id)
+    assert state.state == "off"
+
+    await hass.services.async_call(
+        LIGHT_DOMAIN, "turn_on", {ATTR_ENTITY_ID: entity_id}, blocking=True
+    )
+    bulb.turn_on.assert_called_once_with(transition=1)
+    bulb.turn_on.reset_mock()