Any Ideas why this does not compile: https://github.com/fr1zle/mpp-with-java-test/blob/master/src/test/java/TestKlass.java#L4

Actual compiler output would be helpful

I just found out that it actually compiles in gradle... just not in IDEA somehow

From the project structure I just saw that you want to have additional java tests. Is there a specific reason why?

We are migrating a library to a kotlin mpp, but we have to stay compatible with the java version so we would like to run our existing java tests against the migrated lib

Sounds reasonable. Until now I thought pure java tests were not possible in mpp. And thats probably also what is happening, gradle picks up your tests as a separate source set (which should work fine I guess).

as in

kotlin.sourceSets.jvmTest.kotlin.srcDirs += "src/test/java"

?

Yeah, does it work? I never used the jvmWithJava target, but that would be my idea