def test_startErrorStop(self):
        """
        Error output only gets sent to the stream after the test has stopped.
        """
        self.distReporter.startTest(self.test)
        self.assertEqual(self.stream.getvalue(), "")
        self.distReporter.addError(self.test, "error")
        self.assertEqual(self.stream.getvalue(), "")
        self.distReporter.stopTest(self.test)
        self.assertNotEqual(self.stream.getvalue(), "")

        Error output only gets sent to the stream after the test has stopped.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/_dist/test/test_distreporter.py