Great news! A fresh update for IntelliJ IDEA 2016.3 is coming soon. Today we’ve published its RC build.
In addition to bugfixes, this build updates JUnit 5 support to M3. Note that if you plan to run JUnit 5 M2, you have to either use an earlier version of IntelliJ IDEA, or manually include JUnit 5 M2 dependencies in your classpath (junit-platform-launcher, junit-platform-commons, junit-platform-engine; junit-jupiter-api and junit-jupiter-engine for Jupiter; and junit-vintage-engine for Vintage).
As always, your feedback is very welcome in our issue tracker.