How to mock function returning AnyVal with Mockito in Scala / Specs2?

Question

I would like to stub a function returning AnyVal using Mockito in Scala (Specs2 to be precise), but it doesn't seam to work: ``` import org.specs2.mutable._ import org.specs2.mock._ case class V(s: String) extends AnyVal class A { def f: V = new V("Hello") } class Sample extends Specification with Mockito { "Mockito" should { "mock A" in { val a = mock[A] a.f returns new V("hoge") a.f match { case V("hoge") => success case _ => failure } } } } ``` This fails with: ``` V cannot be returned by f() f() should return String ``` I found kind of workaround (based on which I provided above snippet) using marker interface/trait: https://gist.github.com/mtgto/9251779 but this is not any solution for me, hence it changes returned type (because of mocking/test library issue). Anyone has seen this before and knows how to stub such function?

Accepted Answer

I found one way of stubbing this function - using original Mockito's doReturn with underlying AnyVal's type (String in this case) instead of AnyVal itself, so:

```
org.mockito.Mockito.doReturn("hoge").when(a).f
```

instead of:

```
a.f returns new V("hoge")
```

How to mock function returning AnyVal with Mockito in Scala / Specs2?

Solution

Problem