使用Mockito修改Bean的依赖

摘要：概述在使用单元测试时经常会遇到某些依赖了外部资源，或者想主动绕过真正的方法执行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，设单元测试的方法是的方法和方法，在执行和方法时都会调用的不同方法，即依赖了一个场景是完全对进行

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。

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；

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);
    }
}

public class MockitoDependencyInjectionTestExecutionListener extends DependencyInjectionTestExecutionListener {

    private Set injectFields = new HashSet<>();
    private Map 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);
    }
}

JUnit、Mockito

AopTargetUtils工具类参考 在spring中获取代理对象代理的目标对象工具类