单元测试-如果测试方法过早失败，该如何模拟？

Question

Let's say we have the following trivial example code:

public void doXYZ(UUID uuidA, UUID uuidB, UUID uuidC){

ObjectA objectA = objectAService.read(uuidA);

ObjectB objectB = objectBService.read(uuidB);

    if(!doMatch(objectA, objectB)){
        throw new ObjectsDoNotMatchException(objectA);
    }

    ObjectC objectC = objectCService.read(uuidC);
    objectC.setObjects(objectA, objectB);

    objectJobService.doWork(objectC);

}

And there would be a test case which tests and expects that the exception is thrown due to some matching issues.

Question: is it enough to Mock the first two services + the objectValidationService as all other services would not be reached anyway if the test case works? Or should the objectCService as well as objectJobService also be mocked as they could be called and return a NullPointerException if the test does not work as expected?

I often ask this kind of question if the methods are not as trivial as the shown method but instead have multiple further dependencies which should be mocked as it can be quite much work to produce a valid state for the full path (which is not being tested in this test case) for early failure cases.

Edit: Let's be more concrete. If they should be mocked: would it be enough to not specifiy the return value (eg with when()) and let them just fail or should those mocked and usually not needed services also return valid values?

Answer 1

Yes: All services should be mocked.

You want to be sure that there were no interactions with the objectCService and objectJobService when objects A and B do not match.