单元测试在调试模式下成功,但在正常运行时失败

Question

为什么我的单元测试在调试模式下成功但在正常运行时失败？

public class ExecutorServiceTest extends MockitoTestCase{   
  private int numThreads;
  private ExecutorService pool;
  private volatile boolean interruptedBitSet;

  @Override
  public void setUp() {
    numThreads = 5;
    pool = Executors.newFixedThreadPool(numThreads);
  }

class TaskChecksForInterruptedBit implements Callable<String> {
    @Override
    public String call() throws Exception {
      interruptedBitSet = false;
      while (!Thread.currentThread().isInterrupted()) {
      }
      interruptedBitSet = Thread.currentThread().isInterrupted();
      return "blah";
    }
  }

public void testCancelSetsInterruptedBitInCallable() throws Exception {
    interruptedBitSet = false;
    final Future<String> future = 
        pool.submit(new TaskChecksForInterruptedBit());
    final boolean wasJustCancelled = future.cancel(true);
    assertTrue(wasJustCancelled);

    // Give time for the thread to notice the interrupted bit and set the flag
    Thread.sleep(5000);

    // This succeeds when stepping through w/ a debugger, but fails when running
    // the test straight. WHY?
    assertTrue(interruptedBitSet);

    assertTrue(future.isDone());
    assertTrue(future.isCancelled());
  }
}

Answer 1

原因几乎可以肯定是调试器中的断点停止了主线程，但没有停止任何后台线程 - ExecutorService 中的线程。在 Eclipse 中调试时，您可以更改断点以停止所有线程，而不仅仅是主线程。

当不调试任务时，任务的提交和立即取消是如此之快，以至于您甚至在任务运行一次之前就将其取消。尝试在这些行之间添加睡眠延迟：

final Future<String> future =  pool.submit(new TaskChecksForInterruptedBit());
Thread.sleep(1000);
final boolean wasJustCancelled = future.cancel(true);

Answer 2

您必须确保您的任务确实开始运行。它可能在有机会之前就被取消了。

public class ExecutorServiceTest {
    private int numThreads;
    private ExecutorService pool;
    private volatile boolean interruptedBitSet;
    private static final CountDownLatch latch = new CountDownLatch(1);

    @Before
    public void setUp() {
        numThreads = 5;
        pool = Executors.newFixedThreadPool(numThreads);
    }

    class TaskChecksForInterruptedBit implements Callable<String> {
        @Override
        public String call() throws Exception {
            interruptedBitSet = false;
            latch.countDown();
            while (!Thread.currentThread().isInterrupted()) {
                System.out.println(System.currentTimeMillis());
            }
            System.out.println("haha");
            interruptedBitSet = Thread.currentThread().isInterrupted();
            return "blah";
        }
    }

    @Test
    public void testCancelSetsInterruptedBitInCallable() throws Exception {
        final Future<String> future =
                pool.submit(new TaskChecksForInterruptedBit());
        interruptedBitSet = false;
        latch.await();
        final boolean wasJustCancelled = future.cancel(true);
        Assert.assertTrue(wasJustCancelled);

        // Give time for the thread to notice the interrupted bit and set the flag
        Thread.sleep(5000);

        // This succeeds when stepping through w/ a debugger, but fails when running
        // the test straight. WHY?
        Assert.assertTrue(interruptedBitSet);

        Assert.assertTrue(future.isDone());
        Assert.assertTrue(future.isCancelled());
    }
}