Ok, I think PR1621 is ready to go: https://github.com/apache/calcite/pull/1621 I'm inclined to merge it shortly
The PR converts most of the tests, and by default, it allows JUnit5 only. Certain modules still have "non-trivial" JUnit4 code, and there was an agreement to convert them later. The modules receive junit4 dependency via junit4=true in gradle.properties. --- The most "controversial" change from my point of view is the removal of *Suite* classes. In other words, I have dropped classes like CalciteSuite, FileSuite, PlusSuite, and so on. I guess it is OK, as both Gradle and JUnit5 provide lots of ways to launch tests (e.g. tags are good). The good thing about the removal is it would reduce the number of merge-conflicts, and it would simplify adding new test classes. --- The most notable difference between junit4 and junit5 .assert* is that junit4 has (message, expected, actual) argument order while junit5 uses (expected, actual, message). The latter is better when message is big (e.g. concatenated), and junit5 allows to use lambda, so the message is built only when assertion fails. I've performed argument shuffling with IntelliJ IDEA's "structural search and replace", so it should be OK. Vladimir
