def test_noCompatibilityLayer(self):
        """
        If no compatibility layer is present, imports of gobject and friends
        are disallowed.

        We do this by running a process where we make sure gi.pygtkcompat
        isn't present.
        """
        if _PY3:
            raise SkipTest("Python3 always has the compatibility layer.")

        from twisted.internet import reactor
        if not IReactorProcess.providedBy(reactor):
            raise SkipTest("No process support available in this reactor.")

        result = Deferred()
        class Stdout(ProcessProtocol):
            data = b""

            def errReceived(self, err):
                print(err)

            def outReceived(self, data):
                self.data += data

            def processExited(self, reason):
                result.callback(self.data)

        path = FilePath(__file__).sibling(b"process_gireactornocompat.py").path
        pyExe = FilePath(sys.executable)._asBytesPath()
        # Pass in a PYTHONPATH that is the test runner's os.path, to make sure
        # we're running from a checkout
        reactor.spawnProcess(Stdout(), pyExe, [pyExe, path],
                             env={"PYTHONPATH": ":".join(sys.path)})
        result.addCallback(self.assertEqual, b"success")
        return result

        If no compatibility layer is present, imports of gobject and friends
        are disallowed.

        We do this by running a process where we make sure gi.pygtkcompat
        isn't present.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_gireactor.py