def test_warningsMaskErrors(self):
        """
        L{DirtyReactorAggregateError}s are I{not} reported as errors if the
        L{UncleanWarningsReporterWrapper} is used.
        """
        result = UncleanWarningsReporterWrapper(
            reporter.Reporter(stream=self.output))
        self.assertWarns(UserWarning, self.dirtyError.getErrorMessage(),
                         reporter.__file__,
                         result.addError, self.test, self.dirtyError)
        self.assertEqual(result._originalReporter.errors, [])

        L{DirtyReactorAggregateError}s are I{not} reported as errors if the
        L{UncleanWarningsReporterWrapper} is used.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/test/test_reporter.py