def test_portable(self):
        """
        L{gireactor.PortableGIReactor} doesn't support application
        registration at this time.
        """
        reactor = gireactor.PortableGIReactor()
        self.addCleanup(self.unbuildReactor, reactor)
        app = Gio.Application(
            application_id='com.twistedmatrix.trial.gireactor',
            flags=Gio.ApplicationFlags.FLAGS_NONE)
        self.assertRaises(NotImplementedError,
                          reactor.registerGApplication, app)

        L{gireactor.PortableGIReactor} doesn't support application
        registration at this time.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_gireactor.py