def test_combine(self): board = Board(4, 4) start_single = [2, 2, 0, 0] start_double = [2, 2, 4, 4] end_single = [4, 0, 0, 0] end_double = [4, 0, 8, 0] self.assertEqual(end_single, board._Board__combine(start_single)) self.assertEqual(end_double, board._Board__combine(start_double))