RFR: 8274274: Update JUnit to version 5.8.1 [v5]

[Kevin Rushforth]

On Sat, 25 Sep 2021 13:55:15 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

>> I've added JUnit 5 as a test dependency and made sure that the JUnit 4 tests still work.  Also added a single JUnit 5 tests, and confirmed it works.
>> 
>> I've updated the Eclipse project file for the base module only.
>
> John Hendrikx has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Readd junit declaration in allprojects and set junit version to 4.13.2

I left a few comments on the dependencies. Will review / test the PR later.

One comment about adding new JUnit 5 tests and migrating existing tests. I think there could be value in organizing the tests such that all of the JUnit 5 tests are grouped, rather than mixing tests in the same directory such that some use JUnit 5 and others use JUnit 4. What do you (or others) think? We could either do this with a new JUnit 5 source set in each project, or by using a package naming convention for JUnit 5 tests like we do for robot tests. Maybe `test5.some.pkg`. This needs more thought.

build.gradle line 1953:

> 1951:         testRuntimeOnly(group: "org.junit.vintage", name: "junit-vintage-engine", version: "5.8.1") {
> 1952:             exclude(group: "org.apiguardian", module: "apiguardian-api")
> 1953:         }

As it turns out, `apiguardian` no longer needs to be blocked, so you can restore it if it is easier.

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PR: https://git.openjdk.java.net/jfx/pull/633