def test_noUSerError(self):
        """
        'NO-USER' error should map to the L{ident.NoUser} exception.
        """
        d = defer.Deferred()
        self.client.queries.append((d, 234, 456))
        self.client.lineReceived('234, 456 : ERROR : NO-USER')
        return self.assertFailure(d, ident.NoUser)

        'NO-USER' error should map to the L{ident.NoUser} exception.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_ident.py