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_switch.py

@@ -0,0 +1,58 @@
+"""Tests for the Wemo switch entity."""
+
+import pytest
+
+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
+
+
+@pytest.fixture
+def pywemo_model():
+    """Pywemo LightSwitch models use the switch platform."""
+    return "LightSwitch"
+
+
+async def test_switch_registry_state_callback(
+    hass, pywemo_registry, pywemo_device, wemo_entity
+):
+    """Verify that the switch receives state updates from the registry."""
+    # On state.
+    pywemo_device.get_state.return_value = 1
+    pywemo_registry.callbacks[pywemo_device.name](pywemo_device, "", "")
+    await hass.async_block_till_done()
+    assert hass.states.get(wemo_entity.entity_id).state == STATE_ON
+
+    # Off state.
+    pywemo_device.get_state.return_value = 0
+    pywemo_registry.callbacks[pywemo_device.name](pywemo_device, "", "")
+    await hass.async_block_till_done()
+    assert hass.states.get(wemo_entity.entity_id).state == STATE_OFF
+
+
+async def test_switch_update_entity(hass, pywemo_registry, pywemo_device, wemo_entity):
+    """Verify that the switch performs state updates."""
+    await async_setup_component(hass, HA_DOMAIN, {})
+
+    # On state.
+    pywemo_device.get_state.return_value = 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.
+    pywemo_device.get_state.return_value = 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