如何使另一个线程的 JUnit 测试失败

Question

考虑以下测试代码：

@Test
public void test() throws InterruptedException {
    var latch = new CountDownLatch(1);

    Executors.newSingleThreadExecutor().execute(() -> {
        latch.countDown();
        Assert.fail("Doesn't fail the test");
    });

    latch.await();
}

它打印异常，但通过。

Exception in thread "pool-1-thread-1" java.lang.AssertionError: Doesn't fail the test at org.junit.Assert.fail(Assert.java:89) at MyTest.lambda$test$0(MyTest.java :55) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) at java.基础/java.lang.Thread.run(Thread.java:834)

我试图设置自定义未捕获异常处理程序setUncaughtExceptionHandler((t, e) -> Assert.fail(e.getMessage())) ，但这没有帮助。

Answer 1

您可以使用两个线程都可以访问的外部 state 来执行此操作。 请注意latch.countDown(); 应在更改 state 后添加

    private volatile boolean failed  = false;
    
    @Test
    public void test() throws InterruptedException {
        var latch = new CountDownLatch(1);

        Executors.newSingleThreadExecutor().execute(() -> {
            failed = true;//or false depending on the use case
            latch.countDown();
            
        });

        latch.await();
        if(failed){
            Assert.fail("Doesn't fail the test");
        }
    }

Answer 2

您还可以使用 shutdown + awaitTermination 来确保所有任务都已完成，并使用 try-catch 和 AtomicBoolean 来断言没有“内部”引发 AssertionErrors。

AtomicBoolean failed = new AtomicBoolean(false);
ExecutorService executorService = Executors.newFixedThreadPool(PARALLEL_POOL_SIZE);

// start tasks.. maybe in a loop to generate load..
executorService.execute(() -> {
  try {
    // Test something
    // ..
    // Validate
    assertThat(actual, equalTo(EXPECTED));
  } catch (AssertionError e) {
    failed.set(true);
    throw e;
  }
});

executorService.shutdown();
boolean terminatedInTime = executorService.awaitTermination(5, TimeUnit.SECONDS);
assertTrue(terminatedInTime);
assertFalse(failed.get());