def test_postClassCleanupWithSelectableErrors(self):
        """
        The post-class cleanup method call C{addError} on the result with a
        L{DirtyReactorAggregateError} Failure if there are selectables.
        """
        selectable = "SELECTABLE HERE"
        reactor = StubReactor([], [selectable])
        test = object()
        reporter = StubErrorReporter()
        jan = _Janitor(test, reporter, reactor=reactor)
        jan.postClassCleanup()
        self.assertEqual(len(reporter.errors), 1)
        self.assertEqual(reporter.errors[0][1].value.selectables,
                          [repr(selectable)])

        The post-class cleanup method call C{addError} on the result with a
        L{DirtyReactorAggregateError} Failure if there are selectables.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/test/test_util.py