使用 Mockito Spy 对 ThreadPoolTaskExecutor 进行单元测试 InterruptedException

Question

我正在使用 spring 的 ThreadPoolTaskExecutor 在多线程中执行任务。 class 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 class 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。

单元测试 class 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
    }
}

我将 Spy 用于 ThreadPoolTaskExecutor，因为我在测试中有其他方法可以测试多线程执行的实际行为。当我尝试运行测试方法时，它会在 stubbing spy 上抛出 NullPointerException：

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

异常：

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，问题可能出在我对 Mockito Spy 进行 stub 处理的方式上。但是，我不确定我是否在正确的路径上存根 InterruptedException。有没有人得到如何实现这一目标的示例？

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。实际代码执行许多其他事情，并注入了许多其他 bean - 其中一些是 Test 中的 Mock，一些是 Spy - 取决于我正在测试的内容。我这里只提到了我遇到问题的部分。

Answer 1

终于找到问题了。我真的很接近，只是 Mockito Spy 的使用有点偏离。这是有效的解决方案：

@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());
    }
}

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