JUnit测试意外行为

Question

I have several JUnit tests that I running to test a message parsing system.

Running the tests individually with the 3s timeout is ok - they all pass.

Running the tests all at once causes problems and I frequently see the following error message:

java.lang.AssertionError: Expected <3> but collection size <0>

I can get around this by increasing the timeout to something like 30s, but in this case, I find that Test1 is rerun for some reason. This is what I see in the logs when running Test6 for example and increasing the timeout on runforMilliseconds(3000, () -> messageProcessor.start()); to runforMilliseconds(30000, () -> messageProcessor.start()); ... as a result this a lot of assertion errors:

[ForkJoinPool.commonPool-worker-1] Started parsing Test1
[ForkJoinPool.commonPool-worker-6] Started parsing Test6
[ForkJoinPool.commonPool-worker-2] Started parsing Test2
[ForkJoinPool.commonPool-worker-5] Started parsing Test5
[ForkJoinPool.commonPool-worker-3] Started parsing Test3

This is an example of a unit test:

Test1.java

@Before
public void setUp() throws Exception {
    test1Mapper.deleteAll();
    messageTestMapper.deleteAll();
    setupMessages();
}

@Test
public void Test1() throws Exception {
    messageTestMapper.insertOne(new TestMessage(message1)):
    messageTestMapper.insertOne(new TestMessage(message2)):
    messageTestMapper.insertOne(new TestMessage(message3)):

    runforMilliseconds(3000, () -> messageProcessor.start());
    List<TestMessageDetails) actualTestMessageDetails = test1Mapper.select();
    assertThat(actualTestMessageDetails, hasSize(3));
}

@SneakyThrows
private void runforMilliseconds(int n, Runnable runnable) throws Exception {
    try {
        CompleteableFuture.runAsync(runnable).get(n, TimeUnit.MILLISECONDS);
    }
    catch (TimeoutException e) {
        log.info("End running");
    }
}

How do I resolve this?

Answer 1

Are all of your unit tests using the same test1Mapper and messageTestMapper variables? If so, consider giving each test its own individual mapper variables so that you can run them in parallel without one test affecting the outcome of the others.