Add tests for the wemo component (#44088)

* Add tests for the wemo component.

* Prefer mock tools from tests.async_mock over importing asynctest directly

* Avoid using `entity/entities` except when referring to an `Entity` instance in wemo tests

* Remove the overridden event_loop fixture from the wemo tests

* Patch the library code, not the integration code, in the wemo tests

tests/components/wemo/test_light_bridge.py

@@ -0,0 +1,56 @@
+"""Tests for the Wemo light entity via the bridge."""
+
+import pytest
+import pywemo
+
+from homeassistant.components.homeassistant import (
+    DOMAIN as HA_DOMAIN,
+    SERVICE_UPDATE_ENTITY,
+)
+from homeassistant.const import ATTR_ENTITY_ID, STATE_OFF, STATE_ON
+from homeassistant.setup import async_setup_component
+
+from tests.async_mock import PropertyMock, create_autospec
+
+
+@pytest.fixture
+def pywemo_model():
+    """Pywemo Bridge models use the light platform (WemoLight class)."""
+    return "Bridge"
+
+
+@pytest.fixture(name="pywemo_bridge_light")
+def pywemo_bridge_light_fixture(pywemo_device):
+    """Fixture for Bridge.Light WeMoDevice instances."""
+    light = create_autospec(pywemo.ouimeaux_device.bridge.Light)
+    light.uniqueID = pywemo_device.serialnumber
+    light.name = pywemo_device.name
+    pywemo_device.Lights = {pywemo_device.serialnumber: light}
+    return light
+
+
+async def test_light_update_entity(
+    hass, pywemo_registry, pywemo_bridge_light, wemo_entity
+):
+    """Verify that the light performs state updates."""
+    await async_setup_component(hass, HA_DOMAIN, {})
+
+    # On state.
+    type(pywemo_bridge_light).state = PropertyMock(return_value={"onoff": 1})
+    await hass.services.async_call(
+        HA_DOMAIN,
+        SERVICE_UPDATE_ENTITY,
+        {ATTR_ENTITY_ID: [wemo_entity.entity_id]},
+        blocking=True,
+    )
+    assert hass.states.get(wemo_entity.entity_id).state == STATE_ON
+
+    # Off state.
+    type(pywemo_bridge_light).state = PropertyMock(return_value={"onoff": 0})
+    await hass.services.async_call(
+        HA_DOMAIN,
+        SERVICE_UPDATE_ENTITY,
+        {ATTR_ENTITY_ID: [wemo_entity.entity_id]},
+        blocking=True,
+    )
+    assert hass.states.get(wemo_entity.entity_id).state == STATE_OFF