new_contents: from pyfakefs import fake_filesystem
  from .chdir import chdir
  
  
  def test_chdir(fs):
      os_module = fake_filesystem.FakeOsModule(fs)
  
      fs.CreateDirectory('./folder')
  
      assert os_module.getcwd() == '/'
      with chdir('./folder'):
          assert os_module.getcwd() == '/folder'
      assert os_module.getcwd() == '/'
  
subject: add test for chdir helper