Maybe this is relevant for some of the test framework/library developers.
@natpryce (HamKrest),
@hhariri (Spek),
@raniejade (KSpec),
@sam (kotlintest)
The JUnit 5 team wants to provide a minimal common foundation for JVM testing libraries. Both opentest4j and junit5 are close to a first milestone release (I guess).
https://github.com/ota4j-team/opentest4j#projects-already-contacted