def METHOD_NAME(self):
    start = datetime(2016, 7, 20, 10, 56, 19)
    end = start + timedelta(seconds=35.6)
    self.mock_datetime.utcnow.side_effect = [start, end]
    messages = self.get_log_messages()
    assert len(messages) == 1
    MOCK_OPEN.assert_called_once_with('/tmp/some-log-2016-07-20-10-56-19.log', 'a')