def test_abstractShouldRotate(self):
        """
        L{BaseLogFile.shouldRotate} is abstract and must be implemented by
        subclass.
        """
        log = logfile.BaseLogFile(self.name, self.dir)
        self.addCleanup(log.close)
        self.assertRaises(NotImplementedError, log.shouldRotate)

        L{BaseLogFile.shouldRotate} is abstract and must be implemented by
        subclass.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_logfile.py