def test_touch(self):
        """
        L{server.Session.touch} updates L{server.Session.lastModified} and
        delays session timeout.
        """
        # Make sure it works before startCheckingExpiration
        self.clock.advance(3)
        self.session.touch()
        self.assertEqual(self.session.lastModified, 3)

        # And after startCheckingExpiration
        self.session.startCheckingExpiration()
        self.clock.advance(self.session.sessionTimeout - 1)
        self.session.touch()
        self.clock.advance(self.session.sessionTimeout - 1)
        self.assertIn(self.uid, self.site.sessions)

        # It should have advanced it by just sessionTimeout, no more.
        self.clock.advance(1)
        self.assertNotIn(self.uid, self.site.sessions)

        L{server.Session.touch} updates L{server.Session.lastModified} and
        delays session timeout.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_web.py