Mockito Test case for CompletableFuture.runAsync() which calls void method

Question

I need help to write mockito test case for below method.

public void getCouponAndNotifyAsync(String countryId, String channelId,
        String storeNumber, String clientId, NotificationRequest notificationRequest)
        throws FirestoreException, TurneroServiceException {
    CompletableFuture.runAsync(() -> getCouponAndNotify(countryId, channelId,
            storeNumber, clientId, notificationRequest));
}

Where getCouponAndNotify() is a void method.

Tried below but its not working

@Test
    public void getCouponAndNotifyAsync() throws Exception {
        //doNothing().when(turneroService).getCouponAndNotify(COUNTRYID, CHANNELID, STORENUMBER, CLIENTID, new NotificationRequest("ext_rborse@falabella.cl", "all"));

        CompletableFuture<Void> runAsync = CompletableFuture
                .runAsync(() -> doNothing().when(turneroService).getCouponAndNotify(COUNTRYID, CHANNELID, STORENUMBER, CLIENTID, new NotificationRequest("ext_rborse@falabella.cl", "all")));

        assertTrue(runAsync.isDone());

    }

Updated test cases but still not working.

@Test
    public void getCouponAndNotifyAsync() throws Exception {
        //doNothing().when(turneroService).getCouponAndNotify(COUNTRYID, CHANNELID, STORENUMBER, CLIENTID, new NotificationRequest("ext_rborse@falabella.cl", "all"));

        CompletableFuture<Void> runAsync = CompletableFuture
                .runAsync(() -> doNothing().when(turneroService).getCouponAndNotify(COUNTRYID, CHANNELID, STORENUMBER, CLIENTID, new NotificationRequest("ext_rborse@falabella.cl", "all")));

        assertTrue(ForkJoinPool.commonPool().awaitQuiescence(5, TimeUnit.SECONDS));
        assertTrue(runAsync.isDone());

    }

Are you trying to use a [partial mock](https://stackoverflow.com/questions/14970516/use-mockito-to-mock-some-methods-but-not-others)? You might be better off extending the class in your test and overriding the synchronous method. — David Ehrmann, Mar 28 '19 at 07:12
Where are you calling `getCouponAndNotifyAsync()` in your test? I also don't think the mock works like you think it does. — David Ehrmann, Mar 28 '19 at 07:14
Can you please explain more on this? getCouponAndNotifyAsync() is getting called in controller class. That test is passed. — Rahul, Mar 29 '19 at 06:32

David Ehrmann · Answer 1 · 2019-03-28T07:08:37.880

I assume you're testing getCouponAndNotify() elsewhere so you don't have to worry about it throwing an exception.

What you'll run into is a race condition between getCouponAndNotifyAsync() and getCouponAndNotify() returning. There are a few solutions for this:

Since you're using the common ForkJoinPool, do

assertTrue(ForkJoinPool.commonPool().awaitQuiescence(5, TimeUnit.Seconds));

It waits for the task to finish.

Alternatively, you could inject an ExecutorService and use it as the second parameter to supplyAsync(). You have a few choices: you could use a mock, you could use an ExecutorService that runs with the current thread, or you could inject a standard Executors.newSingleThreadExecutor(), then call shutdown() and awaitTermination() in your test.

You could also return a CompletionStage<Void> from getCouponAndNotifyAsync() that you can wait on in the test.

whatever written before assertTrue in my test case is it fine? — Rahul, Mar 28 '19 at 07:09
Updated the test cases in question, but still its not working — Rahul, Mar 28 '19 at 07:12

score 1 · Answer 2 · answered Sep 03 '20 at 17:33

Let's say you have this code:

public void method() {
        CompletableFuture.runAsync(() -> {
            //logic
            //logic
            //logic
            //logic
        });
    }

Try to refactor it to something like this:

public void refactoredMethod() {
    CompletableFuture.runAsync(this::subMethod);
}

private void subMethod() {
    //logic
    //logic
    //logic
    //logic
}

After that, test the subMethod this way:

org.powermock.reflect.Whitebox.invokeMethod(classInstance, "subMethod"); 
Mockito.verify(...)

This isn't a perfect solution, but it tests all the logic inside your async execution.

achini · Answer 3 · 2021-12-09T04:26:31.277

To verify your asynchronous method is called, you can use

 verify(<<your service>>, **timeout(100)**.times(1))
      .<<your method>>(<< arguments>>);

ex:-

verify(service, **timeout(100)**.times(1))
      .getCouponAndNotify(anyString(), anyString(), anyString(), anyString(), any(NotificationRequest.class));

Refer https://www.javadoc.io/doc/org.mockito/mockito-core/2.2.9/org/mockito/verification/VerificationWithTimeout.html

Mockito Test case for CompletableFuture.runAsync() which calls void method

3 Answers3