def test_installReactor(self):
        """
        L{installReactor} installs a new reactor if none is present.
        """
        with NoReactor():
            newReactor = object()
            installReactor(newReactor)
            from twisted.internet import reactor
            self.assertIs(newReactor, reactor)

        L{installReactor} installs a new reactor if none is present.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_main.py