code: def test_default_protocol(self):
      with shelve.Shelf({}) as s:
          self.assertEqual(s._protocol, pickle.DEFAULT_PROTOCOL)
  
imports: import unittest
  import dbm
  import shelve
  import pickle
  import os
  from test.support import os_helper
  from collections.abc import MutableMapping
  from test.test_dbm import dbm_iterator
  from test import mapping_tests
label_desc: Use image node_id 14 for calling the TestCase obj's underlying member method code with example usage: obj.test_default_protocol() without return types