def test_applicationComponents(self):
        """
        Check L{twisted.application.service.Application} instantiation.
        """
        app = Application('app-name')

        self.assertTrue(verifyObject(IService, IService(app)))
        self.assertTrue(
            verifyObject(IServiceCollection, IServiceCollection(app)))
        self.assertTrue(verifyObject(IProcess, IProcess(app)))
        self.assertTrue(verifyObject(IPersistable, IPersistable(app)))

        Check L{twisted.application.service.Application} instantiation.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/application/test/test_service.py