};
        CrawlingParameterUtil.setUrlQueueService(service);
        assertNotNull(CrawlingParameterUtil.getUrlQueueService());

        // Set to null
        CrawlingParameterUtil.setUrlQueueService(null);

        // Should be null now
        assertNull(CrawlingParameterUtil.getUrlQueueService());
    }

    @SuppressWarnings("unchecked")
    public void test_dataService_setAndGet() {

 *
 * CrawlerContext context = CrawlingParameterUtil.getCrawlerContext();
 * CrawlingParameterUtil.setCrawlerContext(newContext);
 *
 * UrlQueueService<UrlQueue<?>> urlQueueService = CrawlingParameterUtil.getUrlQueueService();
 * CrawlingParameterUtil.setUrlQueueService(newUrlQueueService);
 *
 * DataService<AccessResult<?>> dataService = CrawlingParameterUtil.getDataService();
 * CrawlingParameterUtil.setDataService(newDataService);
 * }

        final CrawlerContext crawlerContext = CrawlingParameterUtil.getCrawlerContext();
        final UrlQueueService<UrlQueue<?>> urlQueueService = CrawlingParameterUtil.getUrlQueueService();
        if (!urlQueueService.visited(urlQueue)) {
            if (checkAccessCount(crawlerContext)) {
                final AccessResult<?> accessResult = createAccessResult(responseData, resultData);