def METHOD_NAME(self):
    data = DataClassWithOptionals(
        optional_str="hello",
        optional_int=42,
        optional_bool=True,
        optional_list=[2, 3, 5],
        optional_dict={"x": 7},
        optional_child=DataClassChildForTest(137),
    )
    self.assertEqual(data, from_json(to_json(data), DataClassWithOptionals))