spring中使用mockito

1 mockito介绍和入门

官方：https://github.com/mockito/mockito

入门：

5分钟了解Mockito http://liuzhijun.iteye.com/blog/1512780

Mockito：一个强大的用于 Java 开发的模拟测试框架 http://www.oschina.net/translate/mockito-a-great-mock-framework-for-java-development

2 spring中正常使用mockito

上demo代码：

 @RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration(locations = { "classpath:testApplicationContext.xml" })
 public class SpringMockitoTest {
  
     @Mock
     private ApiService mockApiService;
  
     @Before
     public void initMocks() {
         MockitoAnnotations.initMocks(this);
         when(mockApiService.test()).thenReturn("ok");
     }
  
     @Test
     public void should_success_when_testApiService() {
         String result = mockApiService.test();
         Assert.assertEquals("ok", result);
     }
 }
  
 @Component
 public class ApiService {
  
     @Autowired
     private TestApiService testApiService;
  
     public String test() {
         String connect = testApiService.connect();
         connect += "test";//test自己的业务
         return connect;
     }
 }
  
 @Component
 public class TestApiService {
     public String connect() {
         return "error";
     }
  
     public String  findFromDb() {
         return "db_data";
     }
 }

正常使用spring和mockito中，我们把需要的mock的ApiService给mock掉，但是我们更想的是把TestApiService中的connect方法mock掉，这样就可以测试我们自己的代码，也就是ApiService中test方法自己的业务。

3 spring中mock任何容器内对象

上面的demo中，我们如何mock掉TestApiService中的test方法？

因为TestApiService是spring容器管理的bean，并且ApiService中使用到TestApiService，所以我们把ApiService中引用的TestApiService替换成我们的mock对象即可。

Spring框架有个反射工具ReflectionTestUtils，可以把一个对象中属性设置为新值，我们可以使用：

ReflectionTestUtils.setField(apiService, "testApiService", spyTestApiService);

把我们mock的testApiService放到apiService中，这样apiService调用就是我们mock的对象了；但是默认spring中apiService对象是代理对象，不能直接把值设置到属性上，所以我们自己写个小的工具类，在最后如下：

ReflectionTestUtils.setField(AopTargetUtils.getTarget(apiService), "testApiService", spyTestApiService);

完整demo：

 @RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration(locations = { "classpath:testApplicationContext.xml" })
 public class SpringMockitoTest {
  
     @Autowired
     private ApiService apiService;
     @Mock
     private TestApiService spyTestApiService;
     @Autowired
     private TestApiService testApiService;
  
     @Before
     public void initMocks() throws Exception {
         MockitoAnnotations.initMocks(this);
         ReflectionTestUtils.setField(AopTargetUtils.getTarget(apiService), "testApiService", spyTestApiService);
         when(spyTestApiService.connect()).thenReturn("ok");
     }
  
     @After
     public void clearMocks() throws Exception {
         ReflectionTestUtils.setField(AopTargetUtils.getTarget(apiService), "testApiService", testApiService);
     }
  
     @Test
     public void should_success_when_testApiService() {
         String result = apiService.test();
         Assert.assertEquals("oktest", result);
     }
 }
  
 @Component
 public class ApiService {
  
     @Autowired
     private TestApiService testApiService;
  
     public String test() {
         String connect = testApiService.connect();
         connect += "test";//test自己的业务
         return connect;
     }
 }
  
 @Component
 public class TestApiService {
     public String connect() {
         return "error";
     }
  
     public String  findFromDb() {
         return "db_data";
     }
 }
  
 public class AopTargetUtils {
     /**
      * 获取 目标对象
      * @param proxy 代理对象
      * @return 
      * @throws Exception
      */
     public static Object getTarget(Object proxy) throws Exception { 
         if(!AopUtils.isAopProxy(proxy)) { 
             return proxy;//不是代理对象 
         } 
         if(AopUtils.isJdkDynamicProxy(proxy)) { 
             return getJdkDynamicProxyTargetObject(proxy); 
         } else { //cglib 
             return getCglibProxyTargetObject(proxy); 
         } 
     } 
  
     private static Object getCglibProxyTargetObject(Object proxy) throws Exception { 
         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); 
         Object target = ((AdvisedSupport)advised.get(dynamicAdvisedInterceptor)).getTargetSource().getTarget(); 
         return target; 
     } 
  
  
     private static Object getJdkDynamicProxyTargetObject(Object proxy) throws Exception { 
         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); 
         Object target = ((AdvisedSupport)advised.get(aopProxy)).getTargetSource().getTarget(); 
         return target; 
     } 
 }

最后就是注意测试之后要还原现场，把spring对象还原，尤其在跑maven test的时候，否则可能会影响其他人的测试。