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

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

    public void test_crawlerContext_setAndGet() {
        // Initially should be null
        assertNull(CrawlingParameterUtil.getCrawlerContext());

        // Create and set a CrawlerContext
        CrawlerContext context = new CrawlerContext();