Add optimistic updates for Indevolt (#173091)

tests/components/indevolt/test_select.py

@@ -62,12 +62,8 @@ async def test_select_option(
     # Reset mock call count for this iteration
     mock_indevolt.set_data.reset_mock()
 
-    # Update mock data to reflect the new value
-    mock_indevolt.fetch_data.return_value[IndevoltConfig.READ_ENERGY_MODE] = (
-        expected_value
-    )
-
     # Attempt to change option
+    fetch_count_before = mock_indevolt.fetch_data.call_count
     await hass.services.async_call(
         SELECT_DOMAIN,
         SERVICE_SELECT_OPTION,
@@ -80,7 +76,8 @@ async def test_select_option(
         IndevoltConfig.WRITE_ENERGY_MODE, expected_value
     )
 
-    # Verify updated state
+    # Verify state updated optimistically without a new fetch
+    assert mock_indevolt.fetch_data.call_count == fetch_count_before
     assert (state := hass.states.get("select.cms_sf2000_energy_mode")) is not None
     assert state.state == option