使用Mockito修改Bean的依赖
概述 在使用单元测试时经常会遇到某些dependency依赖了外部资源，或者想主动绕过真正的方法执行mock返回结果而快速得到单元测试最终的期望结果，可能有以下两种场景， 对于TestCase A，设单元测试的方法是Service A的execute1方法和execute2方法，在执行execute1和execute2方法时都会调用ServiceB的不同方法，即ServiceA依赖了ServiceB；一个场景是完全对ServiceB进行Mock，如单元测试ServiceA#execute1方法时都通过Mock返回结果；一个场景是部分ServiceB的方法执行真实的业务逻辑（如查询数据库），一部分方法执行Mock返回结果，或Spy，如如单元测试ServiceA#execute2方法时，只mock ServiceB#b2结果，真正执行ServiceB#b1方法。 对TestCase的Service的依赖Bean的完全Mock 当对ServiceA的方法执行单元测试时，如ServiceA -> ServiceB，此时对ServiceB进行Mock，然后将其设置到ServiceA的属性中；后续ServiceA调用ServiceB的方法都降得到Mock后的结果；而对于ServiceB对象的本来的依赖本案暂且将其忽略，后续改进； 思路是在TestCase中依赖ServiceA的同时标示Mock ServiceB，待TestCase依赖注入完成后，新建ServiceB的Mock对象替换ServiceA中的ServiceB依赖； @TestExecutionListeners({MockitoDependencyInjectionTestExecutionListener.class}) publicclassAServiceMockTestextendsBaseTest{ @Mock privateBServicebservice; @Autowired privateAServiceaservice; @Before publicvoidsetup(){ doReturn("mock").when(bservice).b1(); } @Test publicvoidtest(){ a.execute1(); } } @Service publicclassAServiceImplimplementsAService{ @Autowired privateBServicebservice; @Override publicStringexecute1(){ returnbservice.b1();//willreturnmockafterMock } } 当a.execute()执行时将调用aservice的属性bservice的b1方法，返回结果就是在setup方法中指定的结果； 监听TestCase的Service的依赖Bean 当对ServiceA进行单元测试时，依赖了ServiceB，需要获取ServiceB的b1方法的真正执行结果，Mock b2方法的结果，此时可以采用Spy方式；由于ServiceA依赖了ServiceB，而这个属性可能是个AopProxy对象，并不能直接使用Mockito.mock(bservice)或者Mockito.spy(bservice)，所以这里@Spy注解指定的是实现类，通过MockitoDependencyInjectionTestExecutionListener处理后，获得一个Spy对象，同时这个Spy对象设置到bservice（AopProxy对象）中去； @TestExecutionListeners({MockitoDependencyInjectionTestExecutionListener.class}) publicclassAServiceMockTestextendsBaseTest{ @Spy privateBServiceImplbserviceImpl; @Autowired privateAServiceaservice; @Before publicvoidsetup(){ doReturn(true).when(bserviceImpl).b2(any(String.class)); } @Test publicvoidtest(){ a.execute(); } } @Service publicclassAServiceImplimplementsAService{ @Autowired privateBServicebservice; @Override publicbooleanexecute2(){ Stringstr=bservice.b1(); returnbservice.b2(str); } } MockitoDependencyInjectionTestExecutionListener的实现 publicclassMockitoDependencyInjectionTestExecutionListenerextendsDependencyInjectionTestExecutionListener{ privateSet<Field>injectFields=newHashSet<>(); privateMap<String,Object>mockObjectMap=newHashMap<>(); @Override protectedvoidinjectDependencies(TestContexttestContext)throwsException{ super.injectDependencies(testContext); init(testContext); } /** *whenAdependencesonB *mockBorSpyontargetObjectofbeangetfromSpringIoCContainerwhosetypeisB.classorbeanNameisBImpl *@paramtestContext */ privatevoidinit(TestContexttestContext)throwsException{ AutowireCapableBeanFactoryfactory=testContext.getApplicationContext().getAutowireCapableBeanFactory(); Objectbean=testContext.getTestInstance(); Field[]fields=bean.getClass().getDeclaredFields(); for(Fieldfield:fields){ Annotation[]annotations=field.getAnnotations(); for(Annotationannotation:annotations){ if(annotationinstanceofMock){ Class<?>clazz=field.getType(); Objectobject=Mockito.mock(clazz); field.setAccessible(true); field.set(bean,object); mockObjectMap.put(field.getName(),object); }elseif(annotationinstanceofSpy){ Objectfb=factory.getBean(field.getName());//maybeaproxythatcannotbespybecause$Proxyisfinal ObjecttargetSource=AopTargetUtils.getTarget(fb); ObjectspyObject=Mockito.spy(targetSource); if(!fb.equals(targetSource)){//proxy if(AopUtils.isJdkDynamicProxy(fb)){ setJdkDynamicProxyTargetObject(fb,spyObject); }else{//cglib setCglibProxyTargetObject(fb,spyObject); } }else{ mockObjectMap.put(field.getName(),spyObject); } field.setAccessible(true); field.set(bean,spyObject); }elseif(annotationinstanceofAutowired){ injectFields.add(field); } } } for(Fieldfield:injectFields){ field.setAccessible(true); Objectfo=field.get(bean); if(AopUtils.isAopProxy(fo)){ ClasstargetClass=AopUtils.getTargetClass(fo); if(targetClass==null) return; ObjecttargetSource=AopTargetUtils.getTarget(fo); Field[]targetFields=targetClass.getDeclaredFields(); for(FieldtargetField:targetFields){ targetField.setAccessible(true); if(mockObjectMap.get(targetField.getName())==null){ continue; } ReflectionTestUtils.setField(targetSource,targetField.getName(),mockObjectMap.get(targetField.getName())); } }else{ ObjectrealObject=factory.getBean(field.getType()); if(null!=realObject){ Field[]targetFields=realObject.getClass().getDeclaredFields(); for(FieldtargetField:targetFields){ targetField.setAccessible(true); if(mockObjectMap.get(targetField.getName())==null){ continue; } ReflectionTestUtils.setField(fo,targetField.getName(),mockObjectMap.get(targetField.getName())); } } } } } privatevoidsetCglibProxyTargetObject(Objectproxy,ObjectspyObject)throwsNoSuchFieldException,IllegalAccessException{ Fieldh=proxy.getClass().getDeclaredField("CGLIB$CALLBACK_0"); h.setAccessible(true); ObjectdynamicAdvisedInterceptor=h.get(proxy); Fieldadvised=dynamicAdvisedInterceptor.getClass().getDeclaredField("advised"); advised.setAccessible(true); ((AdvisedSupport)advised.get(dynamicAdvisedInterceptor)).setTarget(spyObject); } privatevoidsetJdkDynamicProxyTargetObject(Objectproxy,ObjectspyObject)throwsNoSuchFieldException,IllegalAccessException{ Fieldh=proxy.getClass().getSuperclass().getDeclaredField("h"); h.setAccessible(true); AopProxyaopProxy=(AopProxy)h.get(proxy); Fieldadvised=aopProxy.getClass().getDeclaredField("advised"); advised.setAccessible(true); ((AdvisedSupport)advised.get(aopProxy)).setTarget(spyObject); } } 附 maven依赖 JUnit、Mockito
