More descriptive failure message using custom matcher with mockedResource.expects(where(???)) in ScalaMock

Question

I'm working with ScalaMock and ScalaTest to put together some unit tests. I want to use the ScalaMock's expectation syntax to confirm that the service I'm working on passes along acceptable Json to a mocked resource. In this case acceptable means some internal fields can be different, so I've written a custom function to determine whether the fields I care about match. The problem with this is that it produces relatively unhelpful logging when the expectations are not fulfilled. The expectations set as in:

(mockedResource.doAThing(_: Json)(_: SomeImplicitThing))
  .expects(
    where(
      jsonSimilarAndImplicitEqual(
        expectedJson,
        anInstanceOfImplicitThing
      )(_, _)
    )
  )

Produce the following logging on failure:

- should forward acceptable Json to the mockedResource
  Unsatisfied expectation:

  Expected:
  [info]   inAnyOrder {
  [info]     <mock-1> MockedResource.doAThing<function1> once (never called - UNSATISFIED)
  [info]   }

I'd like to be able to provide some custom logging function to describe why jsonSimilarAndImplicitEqual evaluated to false in a sensible place. I was hoping an inAnyOrderWithLogging block would prove sufficient, but it turns out I can't even use this construct, since it is not supported for AsyncMockFactory.

score -1 · Answer 1 · answered May 04 '18 at 18:23

You could use specs2-mock (a wrapper for Mockito) instead of ScalaMock, and use an argument captor. Using the org.specs2.Mockito trait, you can write val captor = capture[String] and then there was one(value).method(captor.capture). Once you've captured the argument, you can use scalatest Matchers to do assert the relevant properties.

More descriptive failure message using custom matcher with mockedResource.expects(where(???)) in ScalaMock

1 Answers1