'Missing permissions to a directory is an error'

def test_missing_permission_to_directory(self):

    directory = self.mkdir(u'no-permission')
    os.chmod(directory, 0)
    (result, errors) = path.find_mtimes(self.tmpdir)
    self.assertEqual({}, result)
    self.assertEqual({directory: tests.IsA(exceptions.FindError)}, errors)
