code: def test_command_line_handling_do_discovery_uses_default_loader(self):
      program = object.__new__(unittest.TestProgram)
      program._initArgParsers()
  
      class Loader(object):
          args = []
  
          def discover(self, start_dir, pattern, top_level_dir):
              self.args.append((start_dir, pattern, top_level_dir))
              return "tests"
  
      program.testLoader = Loader()
      program._do_discovery(["-v"])
      self.assertEqual(Loader.args, [(".", "test*.py", None)])
  
imports: import os.path
  from os.path import abspath
  import re
  import sys
  import types
  import pickle
  from test import support
  from test.support import import_helper
  import unittest
  import unittest.mock
  import test.test_unittest
label_desc: Use image node_id 19 for calling the TestDiscovery obj's underlying member method code with example usage: obj.test_command_line_handling_do_discovery_uses_default_loader() and returns: str