def test_anonymous(self):
        """
        L{ftp.BaseFTPRealm} returns an L{ftp.FTPAnonymousShell} instance for
        anonymous avatar requests.
        """
        anonymous = self.mktemp()
        realm = ftp.BaseFTPRealm(anonymous)
        iface, avatar, logout = realm.requestAvatar(
            checkers.ANONYMOUS, None, ftp.IFTPShell)
        self.assertIsInstance(avatar, ftp.FTPAnonymousShell)
        self.assertEqual(avatar.filesystemRoot, filepath.FilePath(anonymous))

        L{ftp.BaseFTPRealm} returns an L{ftp.FTPAnonymousShell} instance for
        anonymous avatar requests.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_ftp.py