def test_hash(self, create_mock):
field = ChallengeField('md5')
field._hash('message', b'salt')
create_mock.assert_called_with('message', hashlib.md5, salt=b'salt')
def test_to_python_str(self):
field = ChallengeField('md5')
field._hash = MagicMock()
field.to_python(None, 'message')
field._hash.assert_called_with('message')