def METHOD_NAME(self):
    with pytest.raises(Exception) as excinfo:
        raise PurgeOnlyOneOfAgeAndSize()
    assert excinfo.type is PurgeOnlyOneOfAgeAndSize
    assert issubclass(excinfo.type, BadRequest)
    try:
        raise PurgeOnlyOneOfAgeAndSize()
    except Exception as ex:
        assert ex.__class__ is PurgeOnlyOneOfAgeAndSize
        assert issubclass(ex.__class__, BadRequest)
        assert 400 == ex.code
        assert "Purge must specify only one of age or size" == ex.message