docstr: Tests default arguments
docstr_tok: ["Tests","default","arguments"]
code: def test_main_default_argument_values(self, mock_login):
      """
      Tests default arguments
      """
  
      # Good env
      env = {
          "DOCKERHUB_SECRET_ENDPOINT_URL": "url",
          "DOCKERHUB_SECRET_ENDPOINT_REGION": "region",
      }
      with patch.dict(os.environ, env):
          main(["--secret-name", "name"])
          assert mock_login.call_args_list == [
              call("name", "url", "region")
          ]
  
      # Bad envs - none or not all required vars defined
      tests = [
          {},
          {"DOCKERHUB_SECRET_ENDPOINT_URL": "url"},
          {"DOCKERHUB_SECRET_ENDPOINT_REGION": "region"},
      ]
      for bad_env in tests:
          with patch.dict(os.environ, bad_env):
              with self.assertRaises(RuntimeError):
                  main(["--secret-name", "name"])
  
file_path: mxnet/ci/test_docker_login.py
imports: import os
  import subprocess
  import unittest
  from unittest.mock import create_autospec, patch, call, MagicMock
  import boto3
  from boto3 import client
  from botocore.stub import Stubber
  from docker_login import login_dockerhub, logout_dockerhub, main, DOCKERHUB_RETRY_SECONDS, DOCKERHUB_LOGIN_NUM_RETRIES
label_desc: Use image node_id 7 for calling the TestDockerLogin obj's underlying member method code with example usage: obj.test_main_default_argument_values(mock_login) without return types