Possibly add native Scala mocking

[MrPowers]

It might be nice to add a native Scala mocking solution to MUnit. Your scalameta expertise might help ;)

I asked about the future of mocking in Scala and it seems like most folks use mockito-scala.

Looks like mockito-scala might only work with scalatest and specs2 - not sure.

ScalaMock can only mock traits and no-args classes . It looks like they were waiting for scala.meta to be released and then the project lost steam.

I found it easier to write mocks in other languages:

• Python has mocking built into unittest. unittest is built into Python, so all Python projects have easy access to mocking.
• Ruby's rspec mocking is the best mocking syntax / framework I've worked with. Mocking in RSpec didn't require detailed thought like it does for other frameworks.

Let me know what you think!

[olafurpg]

Thank you for reporting! I don’t have any experience with mocking so I’m not familiar with what a library like mockito provides. My understanding is that mocking is helpful in certain kinds of codebases but mocking can often be avoided by using a different design (which might be more idiomatic Scala)

[MrPowers]

@olafurpg - Here's a code snippet where mocking would be useful:

def sendMessageToSlack(text: String): Unit = {
  val slackApi = new SlackApi("someString")
  val slackMessage = new SlackMessage()
  slackMessage.setText(text)
  slackApi.call(slackMessage)
}

def mySillyFunction(): Int = {
  val res = 2 + 2
  sendMessageToSlack("We just computed 2 + 2!!!")
  res
}

Think you need mocking to be able to test sendMessageToSlack and mySillyFunction. In mySillyFunction, we don't actually want to run the sendMessageToSlack method. We just want to make sure that the method would be invoked with the argument "We just computed 2 + 2!!!".

I haven't used mockito-scala yet either. I will create a sample project and a blog post to discuss the key features. Will report back on this issue with my findings ;)

[olafurpg]

After more consideration I believe mocking is outside the scope of this library. I'm open to add integration modules with existing mocking libraries if there's demonstrable value (like with munit-scalacheck). I think any remotely interesting mocking library will quickly outgrow MUnit in complexity to merit a separate repo.

[MrPowers]

Sounds good, thanks for considering this.

[FloWi]

My understanding is that mocking is helpful in certain kinds of codebases but mocking can often be avoided by using a different design (which might be more idiomatic Scala)

Hi @olafurpg! Would you mind elaborating on that? In my scenario I have a complex trait generated by smithy4s and I would like to mock only a handful of functions for a certain test. I'd be interested in knowing how to do that the idiomatic scala way.

Edit: In case anyone else reads this who is using smithy4s - they thought about that already and you can use this feature. So my problem is solved already, but I'm still curious on how to tackle this the scala-way.