def test_calc_bounding_box(self):
ip = Image_operations()
min_x, max_x, min_y, max_y = ip.calc_bounding_box([(0, 0), (1, 4), (2, -1), (3, 3)])
self.assertEqual(min_x, 0)
self.assertEqual(max_x, 3)
self.assertEqual(min_y, -1)
self.assertEqual(max_y, 4)
