Mockito's Answer in ScalaTest

Question

Is there some alternative to Mockito's Answer in ScalaTest? I was going through its documentation, but didn't find anything.

I would like to, for example, execute some logic on arguments of a stubbed method. In Mockito, I would do something like this:

when(mock.create(any(A.class))).thenAnswer(new Answer() {
    Object answer(InvocationOnMock invocation) {
        A firstArg = (A) invocation.getArguments()[0];
        firstArg.callMethod();
        return null;
    }
});

In ScalaTest, I'm fine with using Mockito, as well. However, it would be nice if there was some more Scala-friendly syntax of defining such Answer.

Thank you.

It would help if you let us know what exactly you find to be deficient. — rs_atl, Feb 22 '13 at 14:10

score 11 · Answer 1 · answered Oct 14 '16 at 13:26

I just found this blog post. It describes how to use implicit conversions to achieve what you want. If you define an implicit conversion like this

implicit def toAnswerWithArgs[T](f: InvocationOnMock => T) = new Answer[T] {
    override def answer(i: InvocationOnMock): T = f(i)
}

you can call thenAnswer with a simple function as argument:

when(mock.someMethodCall()).thenAnswer((i) => calculateReturnValue())

There is also a slightly shorter alternative version for the case when your mocked method has no arguments. Follow the link for details.

So much cleaner as, after adding the implicits, doReturn can be replaced directly with doAnswer when the return value need recomputation on request. — Pyrce, Apr 19 '18 at 20:22

score 3 · Answer 2 · answered Sep 29 '16 at 21:39

Define this helper function:

def answer[T](f: InvocationOnMock => T): Answer[T] = {
  new Answer[T] {
    override def answer(invocation: InvocationOnMock): T = f(invocation)
  }
}

And use it like this, e.g. for returning a Future[MyClass] containing any argument passed to a method:

when(myRepository.create(any[MyClass]())).thenAnswer(answer({ invocation =>
  Future.successful(invocation.getArguments.head.asInstanceOf[MyClass])
}))

score 2 · Answer 3 · answered Feb 22 '13 at 23:02

2

If you mix in the trait MockitoSugar, you can create a mock and and pass it an answer using this syntax:

mock[Collaborator](new Answer(){ ... })

answered Feb 22 '13 at 23:02

yakshaver

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score 1 · Answer 4 · answered Feb 22 '13 at 14:39

1

Have you tried ScalaMock? It is also integrated with ScalaTest and provides a more Scala-friendly API.

answered Feb 22 '13 at 14:39

rs_atl

8,935
1
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I'm in the process of migrating from mockito to ScalaMock, and was wondering how one can actually do something like `InvocationOnMock` in ScalaMock. Turns out it was super easy and just like I would have wanted to do in mockito: just have some impure/mutative function that is wrappen in ScalaMock's `returns`: like `...when(...).returns(updateCount())` – bbarker Oct 26 '17 at 21:25

Mockito's Answer in ScalaTest

4 Answers4

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