def test_missing_arguments(self):
selection_set = _.knows_command
with pytest.raises(quiz.SelectionError) as exc:
quiz.validate(Dog, selection_set)
assert exc.value == quiz.SelectionError(
Dog, 'knows_command', quiz.MissingArgument('command'))
def test_missing_argument_str(name):
exc = quiz.MissingArgument(name)
assert str(exc) == 'argument "{}" missing (required)'.format(name)