SpringCloud升级之路2020.0.x版-24.测试Spring Cloud LoadBalancer

本系列代码地址：https://github.com/HashZhang/spring-cloud-scaffold/tree/master/spring-cloud-iiford

通过单元测试，我们也可以了解下一般我们实现 spring cloud 自定义的基础组件，怎么去单元测试。

这里的单元测试主要测试三个场景：

只返回同一个 zone 下的实例，其他 zone 的不会返回
对于多个请求，每个请求返回的与上次的实例不同。
对于多线程的每个请求，如果重试，返回的都是不同的实例

同时，我们也需要针对同步和异步两个配置，分别进行测试，同步和异步两种配置测试逻辑是一样的，只是测试的 Bean 不一样：

同步环境是 DiscoveryClient，异步环境是 ReactiveDiscoveryClient
同步环境负载均衡器是 LoadBalancer，异步环境负载均衡器是 ReactiveLoadBalancer

同步测试代码请参考：LoadBalancerTest.java，异步测试代码请参考：LoadBalancerTest.java

我们这里使用同步测试代码作为例子展示：

//SpringExtension也包含了MockitoJUnitRunner，所以 @Mock 等注解也生效了@ExtendWith(SpringExtension.class)@SpringBootTest(properties = {LoadBalancerEurekaAutoConfiguration.LOADBALANCER_ZONE + "=zone1"})public class LoadBalancerTest {@EnableAutoConfiguration@Configurationpublic static class App {@Beanpublic DiscoveryClient myDiscoveryClient() {ServiceInstance zone1Instance1 = Mockito.spy(ServiceInstance.class);ServiceInstance zone1Instance2 = Mockito.spy(ServiceInstance.class);ServiceInstance zone2Instance3 = Mockito.spy(ServiceInstance.class);Map<String, String> zone1 = Map.ofEntries(Map.entry("zone", "zone1"));Map<String, String> zone2 = Map.ofEntries(Map.entry("zone", "zone2"));when(zone1Instance1.getMetadata()).thenReturn(zone1);when(zone1Instance1.getInstanceId()).thenReturn("instance1");when(zone1Instance2.getMetadata()).thenReturn(zone1);when(zone1Instance2.getInstanceId()).thenReturn("instance2");when(zone2Instance3.getMetadata()).thenReturn(zone2);when(zone2Instance3.getInstanceId()).thenReturn("instance3");DiscoveryClient spy = Mockito.spy(DiscoveryClient.class);Mockito.when(spy.getInstances("testService")).thenReturn(List.of(zone1Instance1, zone1Instance2, zone2Instance3));return spy;}}@SpyBeanprivate LoadBalancerClientFactory loadBalancerClientFactory;@SpyBeanprivate Tracer tracer;/*** 只返回同一个 zone 下的实例*/@Testpublic void testFilteredByZone() {ReactiveLoadBalancer<ServiceInstance> testService =loadBalancerClientFactory.getInstance("testService");for (int i = 0; i < 100; i++) {ServiceInstance server = Mono.from(testService.choose()).block().getServer();//必须处于和当前实例同一个zone下Assertions.assertEquals(server.getMetadata().get("zone"), "zone1");}}/*** 返回不同的实例*/@Testpublic void testReturnNext() {ReactiveLoadBalancer<ServiceInstance> testService =loadBalancerClientFactory.getInstance("testService");Span span = tracer.nextSpan();for (int i = 0; i < 100; i++) {try (Tracer.SpanInScope cleared = tracer.withSpanInScope(span)) {ServiceInstance server1 = Mono.from(testService.choose()).block().getServer();ServiceInstance server2 = Mono.from(testService.choose()).block().getServer();//每次选择的是不同实例Assertions.assertNotEquals(server1.getInstanceId(), server2.getInstanceId());}}}/*** 跨线程，默认情况下是可能返回同一实例的，在我们的实现下，保持* span 则会返回下一个实例，这样保证多线程环境同一个 request 重试会返回下一实例** @throws Exception*/@Testpublic void testSameSpanReturnNext() throws Exception {Span span = tracer.nextSpan();for (int i = 0; i < 100; i++) {try (Tracer.SpanInScope cleared = tracer.withSpanInScope(span)) {ReactiveLoadBalancer<ServiceInstance> testService =loadBalancerClientFactory.getInstance("testService");ServiceInstance server1 = Mono.from(testService.choose()).block().getServer();AtomicReference<ServiceInstance> server2 = new AtomicReference<>();Thread thread = new Thread(() -> {try (Tracer.SpanInScope cleared2 = tracer.withSpanInScope(span)) {server2.set(Mono.from(testService.choose()).block().getServer());}});thread.start();thread.join();System.out.println(i);Assertions.assertNotEquals(server1.getInstanceId(), server2.get().getInstanceId());}}}}

运行测试，测试通过。