@Test
public void testPoll()
{

   Assert.assertEquals(queue.size(), 0);
   FairQueueTestString s = queue.poll();
   Assert.assertNull(s);
   queue.offer(new FairQueueTestString("key1", "item1"));
   queue.offer(new FairQueueTestString("key1", "item2"));
   queue.offer(new FairQueueTestString("key1", "item3"));
   queue.offer(new FairQueueTestString("key2", "item4"));
   queue.offer(new FairQueueTestString("key2", "item5"));
   Assert.assertEquals(queue.size(), 5);
   s = queue.poll();
   Assert.assertNotNull(s);
   Assert.assertEquals(s.getItem(), "item1");
   Assert.assertEquals(queue.size(), 4);
   s = queue.poll();
   Assert.assertNotNull(s);
   Assert.assertEquals(s.getItem(), "item4");
   Assert.assertEquals(queue.size(), 3);
}