upgrade openapi poms and codegen tests to junit5

[thorstenhirsch]

PR for openapi poms and codegen tests of #18470

[wing328]

lgtm. thanks for the PR

cc @OpenAPITools/generator-core-team

[wing328]

outdated doc updated via 98f9c07

[wing328]

@thorstenhirsch can you please PM me via Slack about this PR when you've time?

[wing328]

UPDATE: I've reverted this change via #18786 (merged) in the latest master as due to the upgrade, all testng tests were skipped silently (even though there are failed assertions)

I tried various solutions to run both junit5 and testng in the same project but no luck.

My take is to migrate junit4 tests to testng as it would be easier to maintain this project with just one testing framework.

[Philzen]

@wing328

all testng tests were skipped silently

i was about to ask about this behavior on slack, as i got the same hunch

I've reverted this change via #18786 (merged) in the latest master

that made me a bit sad when i saw it – as i had the silent hope we'd planning to transition to Junit5 rather than TestNG (oh how i miss the @TempDir annotation which would make many tests so much more concise!) ... also, consumers of v7.6.0 maybe missing the junit5 generation capability that @thorstenhirsch just introduced...

I tried various solutions to run both junit5 and testng in the same project but no luck.

I've tried around a little more and after what felt an eternity was finally successful following https://maven.apache.org/surefire/maven-surefire-plugin/examples/junit-platform.html#How_to_run_TestNG_tests_within_the_JUnit_Platform (using org.junit.support:testng-engine is the key ingredient to ensure the Jupiter test runner picks up the TestNG tests).

I was even able to remove the junit4 dependency from the classpath for good, so one will not be bothered by the org.junit.* stuff in autocompletion (so now there's only two @Test annotations` to choose from instead of three).

See #18790