Add brightness to lightstrip's set_effect (#415)

* Add brightness parameter to lightstrip's set_effect

* Use None as default as effects have different default brightnesses

kasa/smartlightstrip.py

@@ -89,16 +89,19 @@ class SmartLightStrip(SmartBulb):
 
     @requires_update
     async def set_effect(
-        self,
+        self, effect: str, *, brightness: Optional[int] = None
-        effect: str,
     ) -> None:
         """Set an effect on the device.
 
         :param str effect: The effect to set
+        :param int brightness: The wanted brightness
         """
         if effect not in EFFECT_MAPPING_V1:
             raise SmartDeviceException(f"The effect {effect} is not a built in effect.")
-        await self.set_custom_effect(EFFECT_MAPPING_V1[effect])
+        effect_dict = EFFECT_MAPPING_V1[effect]
+        if brightness is not None:
+            effect_dict["brightness"] = brightness
+        await self.set_custom_effect(effect_dict)
 
     @requires_update
     async def set_custom_effect(

kasa/tests/test_lightstrip.py

@@ -30,6 +30,23 @@ async def test_effects_lightstrip_set_effect(dev: SmartLightStrip):
     assert dev.state_information["Effect"] == "Candy Cane"
 
 
+@lightstrip
+@pytest.mark.parametrize("brightness", [100, 50])
+async def test_effects_lightstrip_set_effect_brightness(
+    dev: SmartLightStrip, brightness, mocker
+):
+    query_helper = mocker.patch("kasa.SmartLightStrip._query_helper")
+
+    if brightness == 100:  # test that default brightness works
+        await dev.set_effect("Candy Cane")
+    else:
+        await dev.set_effect("Candy Cane", brightness=brightness)
+
+    args, kwargs = query_helper.call_args_list[0]
+    payload = args[2]
+    assert payload["brightness"] == brightness
+
+
 @lightstrip
 async def test_effects_lightstrip_has_effects(dev: SmartLightStrip):
     assert dev.has_effects is True