def test_combination_has_valid_char(self):
     code = Code()
     allowed_chars = code.allowed_chars
     override_code = SimpleOverride(request_code='624FZ').override_code
     self.assertIsNotNone(override_code)
     for c in override_code:
         self.assertIn(c, allowed_chars)
     for c in code.decode(override_code):
         self.assertIn(c, allowed_chars)