code: def test_message(self):
      message = Message()
      message["text"] = "lol"
      err = None
      try:
          message["text"] = "rofl"
      except RuntimeError as e:
          err = e
      assert err is not None, "Message allowed override"
      message_copy = message.copy()
      assert (
          type(message_copy) == Message
      ), "Message did not copy properly"
  
imports: from parlai.core.message import Message
  import unittest
label_desc: Use image node_id 1 for calling the TestUtils obj's underlying member method code with example usage: obj.test_message() without return types