Migrate tests to JUnit5

[strangelookingnerd]

There are already some tests that already use JUnit5 as well as some pending PRs (#3219, #3218, ...) to migrate more. This PR will migrate all (*) tests to JUnit5.

Migration includes:

• Using JUnit5 annotations
• Using Assertions
• Remove public modifiers from test classes and methods
• Clean up assertions (switching expected and actual, simplyifing assertions...)
• Trivial code cleanup

I validated my changes using ./mvnw verify and

(*) Some tests use org.junit.Rule implementations that do not have a JUnit5 replacement and implementing these is non-trivial from what I can tell. Further there are some instances of other testing frameworks that do not yet support JUnit5. I plan on looking into these cases as well but deliberately did not include them in this PR.

Checklist

• Base your changes on 2.x branch if you are targeting Log4j 2; use main otherwise
• ./mvnw verify succeeds (if it fails due to code formatting issues reported by Spotless, simply run ./mvnw spotless:apply and retry)
• Non-trivial changes contain an entry file in the src/changelog/.2.x.x directory
• Tests for the changes are provided
• Commits are signed (optional, but highly recommended)

[ppkarwasz]

@strangelookingnerd,

It will take me some time to scroll through all the changes in this PR, but I'll try to review this and your other PRs by the end of next week.

[github-actions]

Job	Requested goals	Build Tool Version	Build Outcome	Build Scan®
build-macos-latest	clean install	3.9.8	✅
build-ubuntu-latest	clean install	3.9.8	✅
build-windows-latest	clean install	3.9.8	✅

Generated by gradle/develocity-actions

[ppkarwasz]

@strangelookingnerd,

Do you have a deadline for the "Migrate to JUnit 5" task? We are swamped with work these days, so the review might take more time than anticipated.

[strangelookingnerd]

@strangelookingnerd,

Do you have a deadline for the "Migrate to JUnit 5" task? We are swamped with work these days, so the review might take more time than anticipated.

Not at all. I fully understand that the changeset is quite large and will take its time to review. I still hope that it will be merged eventually and I will try my best to keept it up-to-date and free of merge confilict 👍🏼

[jvz]

I'll review this, especially since converting tests from v4 to v5 was one of my "hobbies" in this project not that long ago.

[jvz]

Had to review this in IntelliJ as the web UI can barely handle this. Unfortunately, I can't approve it from IntelliJ due to some Apache org settings. So here I am back in the web UI to say LGTM.