it seems that a recommended way to mock extensions with Mockk is to define a 

@file:JvmName

 and refer to it with 

mockkStatic("<jvm-name>")

, which is not type safe: In case of refactoring (e.g. rename or package change), the tests might break inadvertently. Is there a more type safe manner to mock extension functions?

yes, it’s a relatively recent addition: https://mockk.io/#extension-functions

ah, I like the alternative using the method reference. It is potentially more code to write (for several extensions), but also more robust

just ran into this, good alternative