code: def test_default_name(self):
      class MyExtension(training.Extension):
          pass
  
      ext = MyExtension()
      self.assertEqual(ext.default_name, "MyExtension")
  
file_path: chainer/tests/chainer_tests/training_tests/test_extension.py
imports: import unittest
  import pytest
  from chainer import testing
  from chainer import training
label_desc: Use image node_id 2 for calling the TestExtension obj's underlying member method code with example usage: obj.test_default_name() without return types