Add iot brightness feature (#808)

kasa/tests/test_feature_brightness.py

@@ -1,7 +1,8 @@
 import pytest
 
+from kasa.iot import IotDevice
 from kasa.smart import SmartDevice
-from kasa.tests.conftest import parametrize
+from kasa.tests.conftest import dimmable, parametrize
 
 brightness = parametrize("brightness smart", component_filter="brightness")
 
@@ -26,3 +27,25 @@ async def test_brightness_component(dev: SmartDevice):
 
     with pytest.raises(ValueError):
         await feature.set_value(feature.maximum_value + 10)
+
+
+@dimmable
+async def test_brightness_dimmable(dev: SmartDevice):
+    """Test brightness feature."""
+    assert isinstance(dev, IotDevice)
+    assert "brightness" in dev.sys_info or bool(dev.sys_info["is_dimmable"])
+
+    # Test getting the value
+    feature = dev.features["brightness"]
+    assert isinstance(feature.value, int)
+    assert feature.value > 0 and feature.value <= 100
+
+    # Test setting the value
+    await feature.set_value(10)
+    assert feature.value == 10
+
+    with pytest.raises(ValueError):
+        await feature.set_value(feature.minimum_value - 10)
+
+    with pytest.raises(ValueError):
+        await feature.set_value(feature.maximum_value + 10)