final OpenSearchUrlQueue urlQueue = new OpenSearchUrlQueue();
        urlQueue.setCreateTime(System.currentTimeMillis());
        urlQueue.setDepth(1);
        urlQueue.setMethod("GET");
        urlQueue.setSessionId("id1");
        urlQueue.setUrl("http://www.id1.com/");

        urlQueueService.insert(urlQueue);

        final OpenSearchUrlQueue urlQueue2 = new OpenSearchUrlQueue();

     */
    @Override
    public OpenSearchUrlQueue poll(final String sessionId) {
        final QueueHolder queueHolder = getQueueHolder(sessionId);
        final Queue<OpenSearchUrlQueue> waitingQueue = queueHolder.waitingQueue;
        final Queue<OpenSearchUrlQueue> crawlingQueue = queueHolder.crawlingQueue;

        OpenSearchUrlQueue urlQueue = waitingQueue.poll();
        if (urlQueue == null) {

        @Override
        public void delete(String sessionId) {
            // Do nothing in test
        }

        @Override
        public void deleteAll() {
            // Do nothing in test
        }

        @Override
        public void offerAll(String sessionId, List<OpenSearchUrlQueue> list) {
            // Do nothing in test