@Override
    public List<Instance> getAllInstances(String serviceName) throws NacosException {
        return getAllInstances(serviceName, new ArrayList<>());
    }
@Test
    void testGetAllInstanceFromFailoverEmpty() throws NacosException {
        when(serviceInfoHolder.isFailoverSwitch()).thenReturn(true);
        ServiceInfo serviceInfo = new ServiceInfo("group1@@service1");
        when(serviceInfoHolder.getFailoverServiceInfo(anyString(), anyString(), anyString())).thenReturn(serviceInfo);
        List<Instance> actual = client.getAllInstances("service1", "group1", false);
        verify(proxy).queryInstancesOfService(anyString(), anyString(), anyString(), anyBoolean());
        assertEquals(0, actual.size());
    }