def test_pad(self):
        bbox = BoundingBox(0, 100, 0, 100).pad(10)
        self.assertEquals(bbox, BoundingBox(-10, 110, -10, 110))

        bbox = BoundingBox(10, 12, 10, 12)
        bbox.pad(-0.8)
        self.assertEquals(bbox, BoundingBox(10.8, 11.2, 10.8, 11.2))
    def test_center(self):
        bbox = BoundingBox(0, 10, 0, 10)

        self.assertEquals(bbox.center(), (5.0, 5.0))

        bbox.pad(500)

        self.assertEquals(bbox.center(), (5.0, 5.0))
    def test_center(self):
        bbox = BoundingBox(0, 10, 0, 10)

        self.assertEquals(bbox.center(), (5.0, 5.0))

        bbox.pad(500)

        self.assertEquals(bbox.center(), (5.0, 5.0))
    def test_pad(self):
        bbox = BoundingBox(0, 100, 0, 100).pad(10)

        self.assertEquals(bbox, BoundingBox(-10, 110, -10, 110))

        bbox = BoundingBox(10, 12, 10, 12)

        bbox.pad(-0.8)
        self.assertEquals(bbox, BoundingBox(10.8, 11.2, 10.8, 11.2))