code: def test_main_noargs(self):
      with patch.object(
          sys, "argv", ["test_script.py"]
      ):  # argv[0] doesn't matter
          opt = _TestScript.main()
      assert opt.get("foo") == "defaultvalue"
      assert opt.get("bar") == "sneaky"
  
imports: import sys
  import unittest
  from unittest.mock import patch
  from parlai.core.params import ParlaiParser
  import parlai.core.script
  import parlai.utils.testing
label_desc: Use image node_id 5 for calling the TestScriptRegistry obj's underlying member method code with example usage: obj.test_main_noargs() without return types