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());
    }