def test_indentError(self):
        """
        'UNKNOWN-ERROR' error should map to the L{ident.IdentError} exception.
        """
        d = defer.Deferred()
        self.client.queries.append((d, 123, 456))
        self.client.lineReceived('123, 456 : ERROR : UNKNOWN-ERROR')
        return self.assertFailure(d, ident.IdentError)

        'UNKNOWN-ERROR' error should map to the L{ident.IdentError} exception.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_ident.py