本系列代码地址：https://github.com/HashZhang/...
通过单元测试，咱们也能够理解下个别咱们实现 spring cloud 自定义的根底组件，怎么去单元测试。
这里的单元测试次要测试三个场景：
- 只返回同一个 zone 下的实例，其余 zone 的不会返回
- 对于多个申请，每个申请返回的与上次的实例不同。
- 对于多线程的每个申请，如果重试，返回的都是不同的实例
同时，咱们也须要针对同步和异步两个配置，别离进行测试，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
咱们这里应用同步测试代码作为例子展现：
//SpringExtension也蕴含了MockitoJUnitRunner，所以 @Mock 等注解也失效了@ExtendWith(SpringExtension.class)@SpringBootTest(properties = {LoadBalancerEurekaAutoConfiguration.LOADBALANCER_ZONE + "=zone1"})public class LoadBalancerTest { @EnableAutoConfiguration @Configuration public static class App { @Bean public 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; } } @SpyBean private LoadBalancerClientFactory loadBalancerClientFactory; @SpyBean private Tracer tracer; /** * 只返回同一个 zone 下的实例 */ @Test public void testFilteredByZone() { ReactiveLoadBalancer<ServiceInstance> testService = loadBalancerClientFactory.getInstance("testService"); for (int i = 0; i < 100; i++) { ServiceInstance server = Mono.from(testService.choose()).block().getServer(); //必须处于和以后实例同一个zone下 Assertions.assertEquals(server.getMetadata().get("zone"), "zone1"); } } /** * 返回不同的实例 */ @Test public 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(); //每次抉择的是不同实例 Assertions.assertNotEquals(server1.getInstanceId(), server2.getInstanceId()); } } } /** * 跨线程，默认状况下是可能返回同一实例的，在咱们的实现下，放弃 * span 则会返回下一个实例，这样保障多线程环境同一个 request 重试会返回下一实例 * * @throws Exception */ @Test public 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。
咱们这一节应用单元测试验证咱们要实现的这些性能是否无效。下一节，咱们将开始剖析同步环境下的 Http 客户端，Open-Feign Client。
微信搜寻“我的编程喵”关注公众号，每日一刷，轻松晋升技术，斩获各种offer：