基于Springboot+Junit+Mockito做单元测试的示例

前⾔

这篇⽂章介绍如何使⽤Springboot+Junit+Mockito做单元测试，案例选取撮合交易的⼀个类来做单元测试。单元测试前先理解需求

要写出好的单测，必须先理解了需求，只有知道做什么才能知道怎么测。但本⽂主要讲mockito的⽤法，⽆需关注具体需求。所以本节略去具体的需求描述。隔离外部依赖

Case1. 被测类中被@Autowired 或 @Resource 注解标注的依赖对象，如何控制其返回值

以被测⽅法 MatchingServiceImpl.java的matching(MatchingOrder buyOrder, MatchingOrder sellOrder)为例被测类MatchingServiceImpl

public class MatchingServiceImpl implements MatchingService {

private static final Logger log = LoggerFactory.getLogger(MatchingServiceImpl.class); @Autowired

private QuoteService quoteService; ...

public MatchingResult matching(MatchingOrder buyOrder, MatchingOrder sellOrder) { int currentPrice = quoteService.getCurrentPriceByProduct(buyOrder.getProductCode()); MatchingResult result = new MatchingResult(); if (sellOrder != null && buyOrder != null &&

sellOrder.getPrice() <= buyOrder.getPrice()) { ... }}

matching⽅法中的quoteService.getCurrentPriceByProduct(buyOrder.getProductCode());要访问Redis获取当前报价，这⾥我们需要把外部依赖quoteService mock掉，控制getCurrentPriceByProduct⽅法的返回值。使⽤mockito可以做到，具体如下：测试类MatchingServiceImplTest

public class MatchingServiceImplTest extends MockitoBasedTest { /**

* 被@Mock标注的对象会⾃动注⼊到被@InjectMocks标注的对象中 */

@Mock

private QuoteService quoteService; /**

*

* 被测对象，⽤@InjectMocks标注，那些被@mock标注的对象就会⾃动注⼊其中。
* 另⼀个注意点是这⾥的MatchingServiceImpl是直接new出来(Mockito 1.9版本后不new也可以)，⽽不是通过spring容器注⼊的。因为这⾥我不需要从spring容器中   * 获得其他依赖，不需要database ，redis ，zookeeper，mq，啥都不依赖，所以直接new   * 

@InjectMocks

private MatchingServiceImpl matchingService = new MatchingServiceImpl(); @Test

public void testMatching_SuccessWhenCurrentPriceBetweenBuyPriceAndSellPrice() { MatchingOrder buyOrder = new MatchingOrder(); buyOrder.setPrice(1000); buyOrder.setCount(23);

MatchingOrder sellOrder = new MatchingOrder(); sellOrder.setPrice(800); sellOrder.setCount(20);

// ⽅法打桩(Method stubbing)

// when(x).thenReturn(y) ：当指定⽅法被调⽤时返回指定值

Mockito.when(quoteService.getCurrentPriceByProduct(Mockito.anyString())).thenReturn(900); MatchingResult result = matchingService.matching(buyOrder, sellOrder); org.junit.Assert.assertEquals(true, result.isSuccess());// 断⾔撮合是否成功 org.junit.Assert.assertEquals(20, result.getTradeCount());// 断⾔成交数量

org.junit.Assert.assertEquals(900, result.getTradePrice()); // 断⾔最新报价是否符合预期 }

Case2. 被测函数A调⽤被测类其他函数B，怎么控制函数B的返回值？

⽐如，MatchingServiceImpl中有个函数startBuyProcess，它⾥⾯调⽤了该类中的其他函数，如getTopSellOrder，matching，如何控制这两个函数的返回值？

这⾥要解决的问题其实是怎么对⼀个类”部分mock”–被测类的被测⽅法（如startBuyProcess）要真实执⾏，⽽另⼀些⽅法（如

getTopSellOrder）则是要打桩（不真正进去执⾏）。被测类MatchingServiceImpl

protected void startBuyProcess(MatchingOrder buyOrder, boolean waitForMatching) { while (true) { //对⼿⽅最优价

MatchingOrder topSellOrder = getTopSellOrder(buyOrder.getProductCode()); MatchingResult matchingResult = matching(buyOrder,topSellOrder); if(matchingResult.isSuccess()) {

doMatchingSuccess(buyOrder,topSellOrder,matchingResult,MatchingType.BUY); if(buyOrder.getCount() <= 0) { break; } }else {

if(waitForMatching) { //加⼊待撮合队列

addToMatchingBuy(buyOrder); }else { //撤单

sendCancleMsg(buyOrder); }

break; } } }

利⽤Mockito.spy()可以做到“部分Mock”

测试类MatchingServiceImplTest.testStartBuyProcess_InCaseOfMatchingSuccess

/** *

* 测试StartBuyProcess⽅法在撮合成功后的处理是否符合预期，即测试startBuyProcess⽅法进⼊下⾯这个判断分⽀后的⾏为 * {@link MatchingServiceImpl#startBuyProcess(MatchingOrder, boolean)} *

*

* if (matchingResult.isSuccess()) {   *
*   doMatchingSuccess(buyOrder, topSellOrder, matchingResult, MatchingType.BUY);   *
*   if (buyOrder.getCount() <= 0) {   *     break;   *   }   * }
* 

public void testStartBuyProcess_InCaseOfMatchingSuccess() { MatchingOrder buyOrder = new MatchingOrder(); buyOrder.setPrice(700); buyOrder.setCount(23);

// ⽤Mockito.spy()对matchingService进⾏部分打桩 matchingService = Mockito.spy(matchingService);

MatchingResult firstMatchingResult = new MatchingResult(); firstMatchingResult.setSuccess(true); firstMatchingResult.setTradeCount(20);

MatchingResult secondMatchingResult = new MatchingResult(); secondMatchingResult.setSuccess(false);

// doReturn(x).when(obj).method() 对⽅法打桩，打桩后，程序执⾏这些⽅法时将按照预期返回指定值，未被打桩的⽅法将真实执⾏ // 两个doReturn表⽰第⼀次调⽤matchingService.matching时返回firstMatchingResult，第⼆次调⽤返回secondMatchingResult // 因为startBuyProcess⾥有个while循坏，可能会多次执⾏matching⽅法

Mockito.doReturn(firstMatchingResult).doReturn(secondMatchingResult).when(matchingService) .matching(Mockito.any(MatchingOrder.class), Mockito.any(MatchingOrder.class)); MatchingOrder sellOrder = new MatchingOrder(); sellOrder.setPrice(600); sellOrder.setCount(20);

// 对getTopSellOrder⽅法打桩

Mockito.doReturn(sellOrder).when(matchingService).getTopSellOrder(Mockito.anyString()); // 对外部依赖jedis的⽅法进⾏打桩

Mockito.when(jedisClient.incrBy(Mockito.anyString(), Mockito.anyLong())).thenReturn(0L); // startBuyProcess是被测函数，不打桩，会真实执⾏ matchingService.startBuyProcess(buyOrder, true);

// 后⾯的校验和断⾔是测试doMatchingSuccess⽅法的⾏为的，这也是这个测试的⽬的

// verify可⽤来校验，某个类的⽅法被执⾏过多少次，这⾥是校验jedisClient.zremFirst是否被执⾏过1次 Mockito.verify(jedisClient, Mockito.times(1)).zremFirst(Mockito.anyString()); org.junit.Assert.assertEquals(3, buyOrder.getCount()); org.junit.Assert.assertEquals(0, sellOrder.getCount()); }

spy的⽤法已经演⽰完毕，下⾯从testStartBuyProcess_InCaseOfMatchingSuccess说下单元测试的“粒度”。

testStartBuyProcess_InCaseOfMatchingSuccess的⽬的是想测doMatchingSuccess，我们费了很⼤劲才把前⾯的⼀堆准备⼯作做完，才能去测doMatchingSuccess。

更好的实践应该是另起测试⽅法去单独测doMatchingSuccess，关注点也集中很多，doMatchingSuccess覆盖完了，再测startBuyProcess其实就只是覆盖下它本⾝的判断分⽀就⾏了。覆盖率照样达到，⽽且测试代码也更容易维

护,testStartBuyProcess_InCaseOfMatchingSuccess由于考虑的职责太多，它很容易受到变化的影响，细⼩的东西改变，可能就会影响它的正常⼯作。引⼊测试框架Maven依赖

junit junit 4.11 test

org.mockito mockito-all 1.10.19 test

org.springframework spring-test 4.2.5.RELEASE test

springboot+junit+mockito的上下⽂构建MockitoBasedTest

@RunWith(SpringJUnit4ClassRunner.class)

@SpringApplicationConfiguration(classes = TestApplication.class)public abstract class MockitoBasedTest { @Before

public void setUp() throws Exception {

// 初始化测试⽤例类中由Mockito的注解标注的所有模拟对象 MockitoAnnotations.initMocks(this); }}

// 其他测试类继承MockitoBasedTest

以上就是本⽂的全部内容，希望对⼤家的学习有所帮助，也希望⼤家多多⽀持。