Would you be able to add a test using the example that failed? (A sealed class with an abstract child?)

Would you be able to add a test using the example that failed? (A sealed class with an abstract child?)

Tried, but that test also succeeded without my modifications. I'm still missing something. Not sure if it's actually related to the abstract class.

Yes the stacktrace helps, thanks, although I can't figure out exactly what's wrong. At least I think it shows that we're on the right path! I don't see any reference to ObjenesisInstantiator.kt. The last MockK code called is in io.mockk.proxy.jvm.transformation.SubclassInstrumentation, so something in there (or earlier) isn't handling sealed subclasses properly. I suspect a similar fix will be needed.

Sorry for commit spam. The current implementation here now seems to fix both, mockk's tests and our own. Please kindly review to spot anything I might have missed.

(I've also hidden a few of my now outdated comments)

So... I tried to add a new test case based on our code and I'm claiming that something in the CI test matrix is currently broken. Have a look at https://github.com/stuebingerb/mockk/pull/10 where the SealedClassTest and SealedInterfaceTest are both running successfully without any adjustments to the implementation.

@aSemy Any idea what might be wrong there?

That is indeed weird! Good catch. I think the new Gradle GHA is re-using the cache for different JDK versions. I see this message in the logs: Task :modules:mockk:test SKIPPED

@Raibaz @aSemy What is needed to get this merged?

I thought that because there was an issue with the Gradle tests not failing #916 (comment) that it wasn't clear if this PR would work as expected.

I don't have any suggestions on how to move forward...

I guess someone will have to fix the CI. But I currently cannot. Until then I'm claiming that this PR will at least improve things and seems to fix the issues for us.

Let's do it then 👍

Ok makes sense, sorry I lost track of what was going on here :)

This change(I guess) breaks mocking a sealed class with kotlin 1.6.21.
In my case the sealed class has abstract class/data class/object childs.