Add device trigger support to sensor entities (#27133)

* Add device trigger support to sensor entities

* Fix typing

* Fix tests, add test helper for comparing lists

tests/testing_config/custom_components/test/sensor.py

@@ -0,0 +1,44 @@
+"""
+Provide a mock sensor platform.
+
+Call init before using it in your tests to ensure clean test data.
+"""
+from homeassistant.components.sensor import DEVICE_CLASSES
+from tests.common import MockEntity
+
+
+ENTITIES = {}
+
+
+def init(empty=False):
+    """Initialize the platform with entities."""
+    global ENTITIES
+
+    ENTITIES = (
+        {}
+        if empty
+        else {
+            device_class: MockSensor(
+                name=f"{device_class} sensor",
+                unique_id=f"unique_{device_class}",
+                device_class=device_class,
+            )
+            for device_class in DEVICE_CLASSES
+        }
+    )
+
+
+async def async_setup_platform(
+    hass, config, async_add_entities_callback, discovery_info=None
+):
+    """Return mock entities."""
+    async_add_entities_callback(list(ENTITIES.values()))
+
+
+class MockSensor(MockEntity):
+    """Mock Sensor class."""
+
+    @property
+    def device_class(self):
+        """Return the class of this sensor."""
+        return self._handle("device_class")