@Override
    public void subscribe(String cluster, NamingListener listener) throws Exception {

    }
@Test
    public void testSubscribe() throws Exception {
        NamingserverRegistryServiceImpl registryService = NamingserverRegistryServiceImpl.getInstance();

        AtomicBoolean isNotified = new AtomicBoolean(false);
        //1.subscribe
        registryService.subscribe(vGroup -> {
            try {
                isNotified.set(true);
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }, "group2");

        //2.register
        InetSocketAddress inetSocketAddress = new InetSocketAddress("127.0.0.1", 8088);
        registryService.register(inetSocketAddress);
        String namespace = FILE_CONFIG.getConfig("registry.namingserver.namespace");
        createGroupInCluster(namespace, "group2", "cluster1");

        //3.check
        assertEquals(isNotified.get(), true);
        registryService.unsubscribe("group2");
    }