that being said, it might be a good idea to switch (or introduce in parallel for all new tests) mockk, which is a mocking library written in Kotlin. It can even mock final classes, which is the default in Kotlin and doesn’t collide with the Kotlin syntax (I ran into the issue of mockito’s when-function colliding with Kotlin’s when keyword yesterday, when working with a project that I recently converted from Java to Kotlin. There is a workaround for that, but still, it’s annoying. So while I don’t want to rewrite all the old tests, i decided to switch to mockk for everythin new. (for completeness: mockito2 has expermental support for mocking final classes as well.) https://mockk.io/