Consider splitting out JUnit 4 functionality into separate module and documenting

[mkobit]

We are in the process of migrating our tests to JUnit 5. Some of the classes here are strongly tied to JUnit 4's execution model. For example DataStreamTestBase

Proposal:

• Split out JUnit 4 specific runners into a separate module
• Add some documentation around using library without inheriting from DataStreamTestBase

A dependency on JUnit 4 is still ok because the JUnit Platform/Jupiter pieces reside in an entirely different, non-conflicting package namespace. A quick peak into the DataStreamTestBase and it looks like some parts are mostly separate, but some documentation and guidance around alternative Runner methods would be very helpful to be able to apply the same model to JUnit 5.

[lofifnc]

I thought I had at least something in the wiki about setting up and running tests by hand. But I'm not able to find the part. I'm going the document the process first.

If I understand correctly Junit 4 and 5 don't bite each other? If I wan't to provide runners for both version maybe I don't have introduce two new modules. Maybe I can just put them in different packages. But I'm not sure what would be more stable and convenient.

[mkobit]

If I understand correctly Junit 4 and 5 don't bite each other?

Yup, you have that correct.

JUnit 5 has a Java 8 base (compared to JUnit 4 which I think, which also seems compatible here since your project uses that as its base too.

This isn't that pressing as we use the vintage engine to run these tests, but would like to eventually move all of our tests to use JUnit Jupiter (or some other JUnit 5 engine) for execution.