[ Proposal ] Unifying testing structure/tools pre-Jackson 3

[JooHyukKim]

Proposal

I propose we unify testing structure/tools pre-Jackson 3 as part of Jackson 3 milestone.

Wrt timing, to not burden other preprations/milestones, this work could be done as late as right before Jackson 3.

Explanation

With bunch of testing improvements being made, expecially with jackson-databind like #243, we now enjoy better test features.

Conversely, we have to deal with different or even incomplete testing environment in other extensions.

[cowtowncoder]

Sounds good. We should probably start adding ideas of improvements we want to roll out from jackson-core and/or jackson-databind to other repos? I think it includes things like (in no particular order)

1. JUnit 5 upgrade
2. "failing" -> "tofix" (with "expected to fail" annotation)

[cowtowncoder]

Another thing I have wondered about (but not done anything :) is whether to publish test jars for jackson-core and/or jackson-databind: that would let us share test code. I think Maven has a way to do that, without multi-project set up but I don't remember details (I think I looked into this with Woodstox 10+ years ago).

But the idea would be that we could have, say, "jackson-core-test" package that provides that "Fail of unit test passes" annotation and perhaps something like "JacksonCoreTestUtil" package with some helper methods, and other modules then have test dependencies to that.
And similar for jackson-databind that has more shareable test functionality.

This would prevent us having to copy-paste that new annotation, for example and reduce existing copy-past test code to some degree (not that it was a huge problem, but nice to have still).

[JooHyukKim]

Yes, sharing test-helper implementations would be great.
I also see value in that we can control how tests would look like?

[JooHyukKim]

Also I think we need scope, like what projects should we include?
Only top N projects then going as necessary?
I guess a few dataformats for as start, but not sure about Kotlin, Scala tho.
Kotlin probably do-able since it uses JUnit I think.
We need to check Scala.

[cowtowncoder]

I think we can propose some ordering; agree wrt dataformats; perhaps jackson-modules-base, jackson-datatypes-collections. Kotlin and Scala modules have separate owners (@k163377 and @pjfanning respectively) and they can decide on what (if anything) to do. I assume Kotlin may follow Jackson core more closely; but testing setup for Scala module is different, f.ex.

[JooHyukKim]

Oh I think also jackson-dataformat-xml wrt dataformats.
Yup Scala seems different.