def test_absolute_sum_of_changes(self):
        self.assertEqualOnAllArrayTypes(absolute_sum_of_changes, [1, 1, 1, 1, 2, 1], 2)
        self.assertEqualOnAllArrayTypes(absolute_sum_of_changes, [1, -1, 1, -1], 6)
        self.assertEqualOnAllArrayTypes(absolute_sum_of_changes, [1], 0)
        self.assertEqualOnAllArrayTypes(absolute_sum_of_changes, [], 0)