code: def test_set_msg_id_when_capturing(self):
      msg_id = "msg-id"
      get_ipython = self._mock_get_ipython(msg_id)
      clear_output = self._mock_clear_output()
  
      with self._mocked_ipython(get_ipython, clear_output):
          widget = widget_output.Output()
          assert widget.msg_id == ""
          with widget:
              assert widget.msg_id == msg_id
          assert widget.msg_id == ""
  
file_path: catboost/contrib/python/ipywidgets/py3/ipywidgets/widgets/tests/test_widget_output.py
imports: import sys
  from unittest import TestCase
  from contextlib import contextmanager
  from IPython.display import Markdown, Image
  from ipywidgets import widget_output
label_desc: Use image node_id 4 for calling the TestOutputWidget obj's underlying member method code with example usage: obj.test_set_msg_id_when_capturing() without return types