newUrlList.add(newUrl1);
        newUrlList.add(newUrl2);

        when(dataHelper.getUrlQueueList(sessionId)).thenReturn(existingQueue);
        when(dataHelper.getAccessResultMap(sessionId)).thenReturn(accessResultMap);

        // Execute
        service.offerAll(sessionId, newUrlList);

        // Verify
        assertEquals(2, existingQueue.size());
    }

                accessResult.setAccessResultData(accessResultData);
            }
            accessResultData.setId(accessResult.getId());

            final Map<String, AccessResultImpl<Long>> arMap = dataHelper.getAccessResultMap(accessResult.getSessionId());
            if (arMap.containsKey(accessResult.getUrl())) {
                throw new CrawlerSystemException(

                }
                return false;
            }
        }

        // check it in result
        final AccessResult<Long> accessResult = dataHelper.getAccessResultMap(urlQueue.getSessionId()).get(url);
        if (accessResult != null) {
            if (logger.isDebugEnabled()) {
                logger.debug("URL exists in a result: {}", url);
            }

     * Creates a new map if one doesn't exist.
     * @param sessionId the session ID
     * @return the access result map for the session
     */
    public synchronized Map<String, AccessResultImpl<Long>> getAccessResultMap(final String sessionId) {
        Map<String, AccessResultImpl<Long>> arMap = sessionMap.get(sessionId);
        if (arMap == null) {
            arMap = new HashMap<>();
            sessionMap.put(sessionId, arMap);