def test_component_bounds_updated(self, mock_method): """ Make sure trait listener for changing component bounds gets set up. """ class TestWindow(AbstractWindow): # needed to avoid a NotImplementedError, not under test def _redraw(self): pass def _get_control_size(self): # this happens in the wild return None thing = Component() TestWindow( parent=None, component=thing, ) thing.bounds = [13.0, 13.0] self.assertTrue(mock_method.called)