    def test_empty_frame(self):
        """
        Check empty Frames still work.
        """
        screen = MagicMock(spec=Screen, colours=8, unicode_aware=False)
        canvas = Canvas(screen, 10, 40, 0, 0)
        scene = Scene([], -1)
        form = _TestFrame3(canvas)
        scene.add_effect(form)
        form.reset()

        # Check all keyboard events get swallowed
        self.assertIsNone(form.process_event(KeyboardEvent(ord("A"))))

        # Check Mouse events over the Frame are swallowed and others allowed
        # to bubble down the input stack.
        self.assertIsNone(
            form.process_event(MouseEvent(20, 5, MouseEvent.LEFT_CLICK)))
        self.assertIsNotNone(
            form.process_event(MouseEvent(5, 5, MouseEvent.LEFT_CLICK)))

        # Check form data is empty.
        form.save()
        self.assertEqual(form.data, {})
Check empty Frames still work.
tests/test_widgets.py