def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def test_regex_flags_bad_input():
    cases = (
        'abcd',
        'ABCabc'
    )

    case_sensitive = inputs.regex(r'^[A-Z]+$')

    for value in cases:
        yield assert_raises, ValueError, lambda: case_sensitive(value)