基于Springboot+Junit+Mockito做单元测试的示例

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()) {
    ...
  }
}

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;
  /**
   * <pre>
   * 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
   * </pre>
   */
  @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
  }

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;
      }
    }
  }

/**
   *
   * 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)}
   *
   * <pre>
   * if (matchingResult.isSuccess()) {
   *
   *   doMatchingSuccess(buyOrder, topSellOrder, matchingResult, MatchingType.BUY);
   *
   *   if (buyOrder.getCount() &lt;= 0) {
   *     break;
   *   }
   * }
   * </pre>
   *
   */
  @Test
  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());
  }

<dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <version>4.11</version>
  <scope>test</scope>
</dependency>

<dependency>
  <groupId>org.mockito</groupId>
  <artifactId>mockito-all</artifactId>
  <version>1.10.19</version>
  <scope>test</scope>
</dependency>
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-test</artifactId>
  <version>4.2.5.RELEASE</version>
  <scope>test</scope>
</dependency>

@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