def test_string_writer_empty(self):
    message = None
    actual = _StringWriter._write(message)
    self.assertIsInstance(actual, _OutputMessage)
    self.assertEqual('""', actual._value)
def test_string_writer_empty(self):
    message = None
    actual = _StringWriter._write(message)
    self.assertIsInstance(actual, _OutputMessage)
    self.assertEqual('', actual._value)