使用 Mockito Spy 对 ThreadPoolTask​​Executor 进行单元测试 InterruptedException

Question

我正在使用 springThreadPoolTaskExecutor在多个线程中执行任务。该类如下所示

    @Component
    public class LoadData {
    //... ...    

        @Inject
        private ThreadPoolTaskExecutor taskExecutor;

        public SomeData getData(Long id) {
            Future<SomeData> loadData = taskExecutor.submit(() -> {
                    //return methodToGetDataSynchronously(id);
                    return new SomeData();
            });
            try {
                SomeData data = loadData.get();
            } catch (InterruptedException | ExecutionException e) {
                logger.error("error");
                //some more processing for the error here
            }
            return data;
       }
  }

为了能够对此类进行单元测试并覆盖InterruptedException和ExecutionException分支，我尝试了多种方法（使用Mockito Spy），但未能成功测试这一点。

单元测试类如下所示：

@RunWith(MockitoJUnitRunner.class)
public class LoadDataTest {

    @InjectMocks
    private LoadData loadData;

    @Spy
    private ThreadPoolTaskExecutor spyTaskExecutor = new ThreadPoolTaskExecutor();

    @Before
    public void init() {
        MockitoAnnotations.initMocks(this);
        spyTaskExecutor.setCorePoolSize(1);
        spyTaskExecutor.setWaitForTasksToCompleteOnShutdown(true);
        spyTaskExecutor.initialize();
    }

    @Test
    public void testGetData_shouldThrowInterruptedException () {
        Mockito.when(spyTaskExecutor.submit(Matchers.<Callable<SomeData>>any())).thenAnswer(new Answer<Future<SomeData>>() {
            public Future<SomeData> answer(InvocationOnMock invocation) throws Throwable {
                Future<SomeData> future = Mockito.mock(FutureTask.class);
                when(future.isDone()).thenReturn(false, false, true);
                when(future.get()).thenThrow(new InterruptedException ());
                return future;
            }
        });

        SomeData result = null;
        result = loadData.getData(101L);
        //verify here that InterruptedException processing was performed
    }
}

我使用SpyforThreadPoolTaskExecutor因为我在测试中有其他方法来测试多线程执行的实际行为。当我尝试运行测试方法时，它会引发NullPointerException存根间谍：

Mockito.when(spyTaskExecutor.submit(Matchers.<Callable<SomeData>>any()))...

例外情况：

java.lang.NullPointerException
    at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:132)
    at org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor.submit(ThreadPoolTaskExecutor.java:320)
at com.company.LoadDataTest.testGetData_shouldThrowInterruptedException(LoadDataTest.java:20)

我想，问题可能出在我阻止 Mockito Spy 的方式上。但是，我不确定我是否走在正确的道路上来存根InterruptedException. 有人有如何实现这一目标的示例吗？

版本：

  jdk-1.8.0_72
  junit-4.12
  mockito-core-1.10.19
  spring-context-4.3.4.RELEASE

注意：这是实际代码的摘录。实际的代码执行许多其他事情，并且注入了许多其他 bean - 其中一些Mock在 中Test，一些在 中Spy- 取决于我正在测试的内容。我只提到了我在这里面临问题的部分。

Answer 1

终于弄清楚问题了。我真的很接近，只是 Mockito Spy 的使用有点偏差。这是工作解决方案：

@RunWith(MockitoJUnitRunner.class)
public class LoadDataTest {

    @InjectMocks
    private LoadData loadData;

    @Spy
    private ThreadPoolTaskExecutor spyTaskExecutor = new ThreadPoolTaskExecutor();

    @Before
    public void init() {
        MockitoAnnotations.initMocks(this);
        spyTaskExecutor.setCorePoolSize(1);
        spyTaskExecutor.setWaitForTasksToCompleteOnShutdown(true);
        spyTaskExecutor.initialize();
    }

    @Test
    public void testGetData_shouldThrowInterruptedException () {
        setupSpyTaskExecutorForException(new InterruptedException("junit"));

        SomeData result = loadData.getData(101L);
        //verify here that InterruptedException processing was performed
    }

    private void setupSpyTaskExecutorForException(Exception e) {
        Mockito.doAnswer(new Answer<Future<?>>() {
            public Future<?> answer(InvocationOnMock invocation) throws Throwable {
                Future<?> future = Mockito.mock(FutureTask.class);
                when(future.get()).thenThrow(e);
                return future;
            }
        }).when(spyTaskExecutor).submit(Matchers.<Callable<?>>any());
    }
}