crawlerContext.setRobotsTxtUrlSet(null);
        assertNull(crawlerContext.getRobotsTxtUrlSet());
    }

    /**
     * Test LRU behavior of robotsTxtUrlSet
     */
    public void test_robotsTxtUrlSet_lru() {
        Set<String> urlSet = crawlerContext.getRobotsTxtUrlSet();

        // Add URLs up to capacity (10000)
        for (int i = 0; i < 10000; i++) {