private void failoverServiceCntMetrics() {
        try {
            for (Map.Entry<String, ServiceInfo> entry : serviceMap.entrySet()) {
                String serviceName = entry.getKey();
                List<Tag> tags = new ArrayList<>();
                tags.add(new ImmutableTag("service_name", serviceName));
                if (Metrics.globalRegistry.find("nacos_naming_client_failover_instances").tags(tags).gauge() == null) {
                    Gauge.builder("nacos_naming_client_failover_instances", () -> serviceMap.get(serviceName).ipCount())
                            .tags(tags).register(Metrics.globalRegistry);
                }
            }
        } catch (Exception e) {
            NAMING_LOGGER.info("[NA] registerFailoverServiceCnt fail.", e);
        }
    }
@Test
    void testFailoverServiceCntMetrics()
            throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        Method method = FailoverReactor.class.getDeclaredMethod("failoverServiceCntMetrics");
        method.setAccessible(true);
        method.invoke(failoverReactor);
        // No exception
    }