Testing using Wiremock to test a Feign Client
So I've spent a good day trying to figure this out and it's been quite difficult. So the issue is that when you have a simple client using Feign as below:
@FeignClient(name = "identity-service")
public interface IdentityClient {
@GetMapping(value = "/")
String request();
}
And of course your application is annotated with the @EnableFeignClients as below:
@EnableEurekaClient
@SpringBootApplication
@EnableFeignClients
public class LicenseServiceApplication {
public static void main(String[] args) {
SpringApplication.run(LicenseServiceApplication.class, args);
}
}
If I have a test for that feign client as below:
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment= SpringBootTest.WebEnvironment.NONE)
public class LicenseServiceTest {
@ClassRule
public static WireMockClassRule wiremock = new WireMockClassRule(
WireMockSpring.options().dynamicPort());
// A service that calls out over HTTP
@Autowired
private IdentityClient identityClient;
// Using the WireMock APIs in the normal way:
@Test
public void contextLoads() throws Exception {
stubFor(get(urlEqualTo("/"))
.willReturn(aResponse().withHeader("Content-Type",
"text/plain").withBody("Hello World!")));
// We're asserting if WireMock responded properly
assertThat(this.identityClient.request()).isEqualTo("Hello World!");
}
}
It generates the following stacktrace:
java.lang.RuntimeException: com.netflix.client.ClientException: Load balancer does not have available server for client: identity-service
at org.springframework.cloud.netflix.feign.ribbon.LoadBalancerFeignClient.execute(LoadBalancerFeignClient.java:71)
at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:97)
at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:76)
at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:103)
at com.sun.proxy.$Proxy122.request(Unknown Source)
at com.gov.zw.service.LicenseServiceTest.contextLoads(LicenseServiceTest.java:34)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
at com.github.tomakehurst.wiremock.junit.WireMockClassRule$1.evaluate(WireMockClassRule.java:70)
at org.junit.rules.RunRules.evaluate(RunRules.java:20)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: com.netflix.client.ClientException: Load balancer does not have available server for client: identity-service
at com.netflix.loadbalancer.LoadBalancerContext.getServerFromLoadBalancer(LoadBalancerContext.java:483)
at com.netflix.loadbalancer.reactive.LoadBalancerCommand$1.call(LoadBalancerCommand.java:184)
at com.netflix.loadbalancer.reactive.LoadBalancerCommand$1.call(LoadBalancerCommand.java:180)
at rx.Observable.unsafeSubscribe(Observable.java:10211)
at rx.internal.operators.OnSubscribeConcatMap.call(OnSubscribeConcatMap.java:94)
at rx.internal.operators.OnSubscribeConcatMap.call(OnSubscribeConcatMap.java:42)
at rx.Observable.unsafeSubscribe(Observable.java:10211)
at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber$1.call(OperatorRetryWithPredicate.java:127)
at rx.internal.schedulers.TrampolineScheduler$InnerCurrentThreadScheduler.enqueue(TrampolineScheduler.java:73)
at rx.internal.schedulers.TrampolineScheduler$InnerCurrentThreadScheduler.schedule(TrampolineScheduler.java:52)
at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber.onNext(OperatorRetryWithPredicate.java:79)
at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber.onNext(OperatorRetryWithPredicate.java:45)
at rx.internal.util.ScalarSynchronousObservable$WeakSingleProducer.request(ScalarSynchronousObservable.java:276)
at rx.Subscriber.setProducer(Subscriber.java:209)
at rx.internal.util.ScalarSynchronousObservable$JustOnSubscribe.call(ScalarSynchronousObservable.java:138)
at rx.internal.util.ScalarSynchronousObservable$JustOnSubscribe.call(ScalarSynchronousObservable.java:129)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
at rx.Observable.subscribe(Observable.java:10307)
at rx.Observable.subscribe(Observable.java:10274)
at rx.observables.BlockingObservable.blockForSingle(BlockingObservable.java:445)
at rx.observables.BlockingObservable.single(BlockingObservable.java:342)
at com.netflix.client.AbstractLoadBalancerAwareClient.executeWithLoadBalancer(AbstractLoadBalancerAwareClient.java:117)
at org.springframework.cloud.netflix.feign.ribbon.LoadBalancerFeignClient.execute(LoadBalancerFeignClient.java:63)
... 35 more
Also do bear in mind I was following the Spring Cloud Contract WireMock documentation here and I looked through their Github examples here. But the results are common in that most tests or implementations are using RestTemplate rather than Feign.
Answer
You should give a static server list to Ribbon which contains localhost.
Firstly you should define your LocalRibbonClientConfiguration as ContextConfiguration at the head of test class.
@RunWith (SpringRunner.class)
@SpringBootTest (classes = TestApplication.class, webEnvironment = WebEnvironment.NONE)
@ContextConfiguration (classes = {LocalRibbonClientConfiguration.class})
Use WiremockClassRule with WireMockConfiguration.
@ClassRule
public static WireMockClassRule wiremock = new WireMockClassRule(WireMockConfiguration.options().dynamicPort());
@TestConfiguration
public static class LocalRibbonClientConfiguration {
@Bean
public ServerList<Server> ribbonServerList() {
return new StaticServerList<>(new Server("localhost", wiremock.port()));
}
}
It goes without problem.