Sehrope>+1 to general clean up of the unit tests. If it's easier to do via JUnit 5 then sure. I'd have that be a separate PR.
I don't intend to rewrite everything to JUnit5 immediately.
PR#1621 enables writing JUnit5 tests, however, it does run all existing JUnit4 tests just fine.
Of course, we can upgrade test by test.
