[pekko-testkit-typed] Support for Junit5

[thmue]

I added a Junit5 Extension to support Junit5 framework integration.

The extension is activated through an annotation:
@ExtendWith(TestKitJunit5Extension.class)
on the class level.

Additionally, a testKit with a @Junit5TestKit annotation needs to be created.
A builder pattern is used to construct the Testkit instance.

@Junit5TestKit
public ActorTestKit testKit = new Junit5TestKitBuilder().build();

The extension itself uses the Junit5 AfterAllCallback to shutdown the testkit after all tests are executed.

I closed the the last PR due to some rebase issues, this PR is directly based on main. Additionally, i discarded the changes in the docs. Sorry for the inconvenience.

[pjfanning]

thanks @thmue - this looks useful.

It does seem a little strange to not support junit5 in the legacy testkit and only in the typed testkit.

[pjfanning]

would it be possible to run scalafmt on the code? We require all PRs to be formatted correctly. The CI build will probably fail.

[thmue]

thank you for your review, i updated the commit after running scalafmt.

Unfortunately i was not aware of the legacy testkit. In case this is not (that much) deprecated/legacy and if you find it useful to support it, i am happy to try to add support to it.
However, i don't see any test framework support in the subproject [pekko-testkit].

[pjfanning]

The CI build is strict about unused imports.

[06-22 09:13:36.548] [error] /home/runner/work/incubator-pekko/incubator-pekko/actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/javadsl/TestKitJunit5Extension.scala:12:19: Unused import
[06-22 09:13:36.549] [error] import org.apache.pekko

[pjfanning]

the build is still failing because of wrong apache headers in new source files - https://github.com/apache/incubator-pekko/actions/runs/5365713746/jobs/9754413547

This text is now wrong

This file is part of the Apache Pekko project, derived from Akka.

Needs to be replaced by

This file is part of the Apache Pekko project, which was derived from Akka.

[thmue]

it seems that the compatibility check for 2.12 is failing due to the usage of

import scala.jdk.CollectionConverters.CollectionHasAsScala

should https://github.com/scala/scala-collection-compat be used or is there another recommended way to convert a list for 2.12 and 2.13?

[pjfanning]

also Scala 3 compile issue -> https://github.com/apache/incubator-pekko/actions/runs/5379239855/jobs/9760373110?pr=445

needs to be (instance: T) => -- you'll need to replace the T with the correct type.

Don't use https://github.com/scala/scala-collection-compat. Try this

import org.apache.pekko
import pekko.util.ccompat._

ccompat is short for collection-compat.

[thmue]

i rebased it, unfortunately i had a lot of build problems. However these could be due to some local setup problems (intellij / scala etc....)