Cache is_supported for Google entities (#73936)

tests/components/google_assistant/test_helpers.py

@@ -327,7 +327,9 @@ async def test_sync_entities_all(agents, result):
 def test_supported_features_string(caplog):
     """Test bad supported features."""
     entity = helpers.GoogleEntity(
-        None, None, State("test.entity_id", "on", {"supported_features": "invalid"})
+        None,
+        MockConfig(),
+        State("test.entity_id", "on", {"supported_features": "invalid"}),
     )
     assert entity.is_supported() is False
     assert "Entity test.entity_id contains invalid supported_features value invalid"
@@ -427,3 +429,34 @@ async def test_config_local_sdk_warn_version(hass, hass_client, caplog, version)
         f"Local SDK version is too old ({version}), check documentation on how "
         "to update to the latest version"
     ) in caplog.text
+
+
+def test_is_supported_cached():
+    """Test is_supported is cached."""
+    config = MockConfig()
+
+    def entity(features: int):
+        return helpers.GoogleEntity(
+            None,
+            config,
+            State("test.entity_id", "on", {"supported_features": features}),
+        )
+
+    with patch(
+        "homeassistant.components.google_assistant.helpers.GoogleEntity.traits",
+        return_value=[1],
+    ) as mock_traits:
+        assert entity(1).is_supported() is True
+        assert len(mock_traits.mock_calls) == 1
+
+        # Supported feature changes, so we calculate again
+        assert entity(2).is_supported() is True
+        assert len(mock_traits.mock_calls) == 2
+
+        mock_traits.reset_mock()
+
+        # Supported feature is same, so we do not calculate again
+        mock_traits.side_effect = ValueError
+
+        assert entity(2).is_supported() is True
+        assert len(mock_traits.mock_calls) == 0