def test_addSlashDeprecated(self):
        """
        L{twisted.web.static.addSlash} is deprecated.
        """
        from twisted.web.static import addSlash

        addSlash(DummyRequest([b'']))

        warnings = self.flushWarnings([self.test_addSlashDeprecated])
        self.assertEqual(len(warnings), 1)
        self.assertEqual(warnings[0]['message'],
            "twisted.web.static.addSlash was deprecated in Twisted 16.0.0")

        L{twisted.web.static.addSlash} is deprecated.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_static.py