def test_margin_minimum_size(self):
        b = BoxLM()
        b.top = DummyElement(Point(4,2))
        b.center = DummyElement(Point(3,4))
        b.bottom = DummyElement(Point(5,1))
        b.margin = 1
        self.assertEqual(b.get_minimum_size(None), Point(5,9))