How does Mockito timeout work?

Question

I'm new to Mockito and JUnit and try to understand basic unit testing with these frameworks. Most concepts in JUnit and Mockito seem straightforward and understandable. However, I got stuck with timeout in Mockito. Does timeout in Mockito play the same role as it does in JUnit? Bellow is my code.

@Mock Timeoutable timeoutable;

@Test(timeout = 100)
public void testJUnitTimeout() {
    try {
        Thread.sleep(2000);
    } catch (InterruptedException ie) { 

    }
}

@Test
public void testMockitoTimeout(){
    doAnswer(new Answer() {
        @Override public Object answer(InvocationOnMock invocation){
            try {
                Thread.sleep(1000);
            } catch (InterruptedException ie){

            }
            return null;
        }
    }).when(timeoutable).longOperation();
    timeoutable.longOperation();
    verify(timeoutable, timeout(100)).longOperation();
}

I expected that both tests failed. But only testJUnitTimeout() failed. Why does the second test pass?

Thank you very much.

Answer 1

Verification with timeout is intended to be used to verify whether or not the operation has been invoked concurrently within the specified timeout.

It provides a limited form of verification for concurrent operations.

The following examples demonstrate the behaviour:

private final Runnable asyncOperation = new Runnable() {
    @Override
    public void run() {
        try {
            Thread.sleep(1000);
            timeoutable.longOperation();
        } catch (InterruptedException e) {
        }
    }

};

@Test
public void testMockitoConcurrentTimeoutSucceeds(){
    new Thread(asyncOperation).start();
    verify(timeoutable, timeout(2000)).longOperation();
}

@Test
public void testMockitoConcurrentTimeoutFails(){
    new Thread(asyncOperation).start();
    verify(timeoutable, timeout(100)).longOperation();
}