def METHOD_NAME(spherical0) -> None:
    vec = FieldVector(**dict(zip(["r", "phi", "theta"], spherical0)))
    dump = json.dumps(vec, cls=NumpyJSONEncoder)
    assert json.loads(dump) == {
        '__class__': FieldVector.__name__,
        '__args__': [vec.x, vec.y, vec.z]
    }