def test_custom_auth_validators_unsupported(self):
        authval1, authval2 = mock.Mock(), mock.Mock()
        expected = ('ResourceOwnerPasswordCredentialsGrant does not '
                    'support authorization validators. Use token '
                              'validators instead.')
        with self.assertRaises(ValueError) as caught:
            ResourceOwnerPasswordCredentialsGrant(self.mock_validator,
                                                  pre_auth=[authval1])
        self.assertEqual(caught.exception.args[0], expected)
        with self.assertRaises(ValueError) as caught:
            ResourceOwnerPasswordCredentialsGrant(self.mock_validator,
                                                  post_auth=[authval2])
        self.assertEqual(caught.exception.args[0], expected)
        with self.assertRaises(AttributeError):
            self.auth.custom_validators.pre_auth.append(authval1)
        with self.assertRaises(AttributeError):
            self.auth.custom_validators.pre_auth.append(authval2)