Add debug logging to homekit when an sensor entity cannot be classified (#142707)

* Add debug logging to homekit when an sensor entity cannot be classified

In #132937 many hours were spent investigating an issue which
turned out to be that the entity did not have a device class
at startup because the group integration does not set the device
class if any of the underlying entities state is invalid.

closes #132937

* coverage

* Update tests/components/homekit/test_get_accessories.py

homeassistant/components/homekit/accessories.py

@@ -245,6 +245,13 @@ def get_accessory(  # noqa: C901
             a_type = "CarbonDioxideSensor"
         elif device_class == SensorDeviceClass.ILLUMINANCE or unit == LIGHT_LUX:
             a_type = "LightSensor"
+        else:
+            _LOGGER.debug(
+                "%s: Unsupported sensor type (device_class=%s) (unit=%s)",
+                state.entity_id,
+                device_class,
+                unit,
+            )
 
     elif state.domain == "switch":
         if switch_type := config.get(CONF_TYPE):

tests/components/homekit/test_get_accessories.py

@@ -53,6 +53,12 @@ def test_not_supported(caplog: pytest.LogCaptureFixture) -> None:
     assert "invalid aid" in caplog.records[0].msg
 
 
+def test_not_supported_sensor(caplog: pytest.LogCaptureFixture) -> None:
+    """Test if none is returned if entity isn't supported."""
+    assert get_accessory(None, None, State("sensor.xyz", "on"), 2, {}) is None
+    assert "Unsupported sensor type (device_class=None)" in caplog.text
+
+
 def test_not_supported_media_player() -> None:
     """Test if mode isn't supported and if no supported modes."""
     # selected mode for entity not supported