def test_call(self):
        """
        L{runner.ErrorHolder} adds an error to the result when called.
        """
        self.holder(self.result)
        self.assertEqual(
            self.result.errors,
            [(self.holder, (self.error.type, self.error.value, self.error.tb))])

        L{runner.ErrorHolder} adds an error to the result when called.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/test/test_runner.py