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})
public class AServiceMockTest extends BaseTest {
@Mock
private BService bservice;
@Autowired
private AService aservice;
@Before
public void setup(){
doReturn("mock").when(bservice).b1();
}
@Test
public void test() {
a.execute1();
}
}
@Service
public class AServiceImpl implements AService {
@Autowired
private BService bservice;
@Override
public String execute1() {
return bservice.b1(); //will return mock after Mock
}
}
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})
public class AServiceMockTest extends BaseTest {
@Spy
private BServiceImpl bserviceImpl;
@Autowired
private AService aservice;
@Before
public void setup(){
doReturn(true).when(bserviceImpl).b2(any(String.class));
}
@Test
public void test() {
a.execute();
}
}
@Service
public class AServiceImpl implements AService {
@Autowired
private BService bservice;
@Override
public boolean execute2() {
String str = bservice.b1();
return bservice.b2(str);
}
}
MockitoDependencyInjectionTestExecutionListener的实现
public class MockitoDependencyInjectionTestExecutionListener extends DependencyInjectionTestExecutionListener {
private Set<Field> injectFields = new HashSet<>();
private Map<String,Object> mockObjectMap = new HashMap<>();
@Override
protected void injectDependencies(TestContext testContext) throws Exception {
super.injectDependencies(testContext);
init(testContext);
}
/**
* when A dependences on B
* mock B or Spy on targetObject of bean get from Spring IoC Container whose type is B.class or beanName is BImpl
* @param testContext
*/
private void init(TestContext testContext) throws Exception {
AutowireCapableBeanFactory factory =testContext.getApplicationContext().getAutowireCapableBeanFactory();
Object bean = testContext.getTestInstance();
Field[] fields = bean.getClass().getDeclaredFields();
for (Field field : fields) {
Annotation[] annotations = field.getAnnotations();
for (Annotation annotation : annotations) {
if(annotation instanceof Mock){
Class<?> clazz = field.getType();
Object object = Mockito.mock(clazz);
field.setAccessible(true);
field.set(bean, object);
mockObjectMap.put(field.getName(), object);
} else if(annotation instanceof Spy) {
Object fb = factory.getBean(field.getName()); //may be a proxy that can not be spy because $Proxy is final
Object targetSource = AopTargetUtils.getTarget(fb);
Object spyObject = Mockito.spy(targetSource);
if (!fb.equals(targetSource)) { //proxy
if (AopUtils.isJdkDynamicProxy(fb)) {
setJdkDynamicProxyTargetObject(fb, spyObject);
} else { //cglib
setCglibProxyTargetObject(fb, spyObject);
}
} else {
mockObjectMap.put(field.getName(), spyObject);
}
field.setAccessible(true);
field.set(bean, spyObject);
}else if (annotation instanceof Autowired){
injectFields.add(field);
}
}
}
for(Field field: injectFields) {
field.setAccessible(true);
Object fo = field.get(bean);
if (AopUtils.isAopProxy(fo)) {
Class targetClass = AopUtils.getTargetClass(fo);
if(targetClass ==null)
return;
Object targetSource = AopTargetUtils.getTarget(fo);
Field[] targetFields =targetClass.getDeclaredFields();
for(Field targetField : targetFields){
targetField.setAccessible(true);
if(mockObjectMap.get(targetField.getName()) ==null){
continue;
}
ReflectionTestUtils.setField(targetSource,targetField.getName(), mockObjectMap.get(targetField.getName()));
}
} else {
Object realObject = factory.getBean(field.getType());
if(null != realObject) {
Field[] targetFields = realObject.getClass().getDeclaredFields();
for(Field targetField : targetFields){
targetField.setAccessible(true);
if(mockObjectMap.get(targetField.getName()) ==null){
continue;
}
ReflectionTestUtils.setField(fo,targetField.getName(), mockObjectMap.get(targetField.getName()));
}
}
}
}
}
private void setCglibProxyTargetObject(Object proxy, Object spyObject) throws NoSuchFieldException, IllegalAccessException {
Field h = proxy.getClass().getDeclaredField("CGLIB$CALLBACK_0");
h.setAccessible(true);
Object dynamicAdvisedInterceptor = h.get(proxy);
Field advised = dynamicAdvisedInterceptor.getClass().getDeclaredField("advised");
advised.setAccessible(true);
((AdvisedSupport) advised.get(dynamicAdvisedInterceptor)).setTarget(spyObject);
}
private void setJdkDynamicProxyTargetObject(Object proxy, Object spyObject) throws NoSuchFieldException, IllegalAccessException {
Field h = proxy.getClass().getSuperclass().getDeclaredField("h");
h.setAccessible(true);
AopProxy aopProxy = (AopProxy) h.get(proxy);
Field advised = aopProxy.getClass().getDeclaredField("advised");
advised.setAccessible(true);
((AdvisedSupport) advised.get(aopProxy)).setTarget(spyObject);
}
}
附
maven依赖
JUnit、Mockito
