btw I think #kotlin should have very strong focus on testing tools, so that it's easy for Java dev to try it and benefit from having DSLs for testing. So it should be really Kotlin frameworks, no such stuff like "final" issue(kotlin really can allow to run tests with special option, not plugin), e.t.c. up to the approach when you counting clicks till writing first tests for existing Java/Maven/gradle project

It's possible to mock

final

classes https://antonioleiva.com/mockito-2-kotlin/

I didnt say its im-possible. Ive get through all this mechanisms in Mockito and PowerMock

what is your main concern, having a relatively easy way to do with Mockito?

i personally find mocks to be code smells. i prefer dependency injection with testing modules to provide any stubs i need.

This approach works only if you can retransform classes in JVM, so works on last JVMs and only if JDK installed. Which is may be fine. Stills looks more like a workaround

Kotlin Test (https://github.com/kotlintest/kotlintest) is an excellent option for Kotlin testing (does more than Unit Testing).