code: @Test public void testSubscribeAndUnsubscribe(){
    NotifyListener listener=new NotifyListener(){
      @Override public void notify(    List<URL> urls){
      }
    }
  ;
    redisRegistry.subscribe(serviceUrl,listener);
    Map<URL,Set<NotifyListener>> subscribed=redisRegistry.getSubscribed();
    assertThat(subscribed.size(),is(1));
    assertThat(subscribed.get(serviceUrl).size(),is(1));
    redisRegistry.unsubscribe(serviceUrl,listener);
    subscribed=redisRegistry.getSubscribed();
    assertThat(subscribed.get(serviceUrl).size(),is(0));
  }
  