Add CSS class tests for check boxes and radio buttons

tests/toggles/test_radiobutton.py

@@ -26,6 +26,11 @@ async def test_radio_button_initial_state() -> None:
             False,
             True,
         ]
+        assert [button.has_class("-on") for button in pilot.app.query(RadioButton)] == [
+            False,
+            False,
+            True,
+        ]
         assert pilot.app.events_received == []
 
 
@@ -39,6 +44,11 @@ async def test_radio_button_toggle() -> None:
             True,
             False,
         ]
+        assert [button.has_class("-on") for button in pilot.app.query(RadioButton)] == [
+            True,
+            True,
+            False,
+        ]
         await pilot.pause()
         assert pilot.app.events_received == [
             ("rb1", True),