def METHOD_NAME(db):
    questionset = QuestionSet.objects.first()
    validator = QuestionSetUniqueURIValidator()
    validator.set_context(QuestionSetSerializer(instance=questionset))
    with pytest.raises(RestFameworkValidationError):
        validator({
            'uri_prefix': questionset.uri_prefix,
            'key': questionset.section.questionsets.last().key,
            'section': questionset.section
        })