Migrate log4j-jul to JUnit 5

[AlbaHerrerias]

Hello 👋

We are from Neighbourhoodie, the implementation partner of the STF Bug Resilience Program. This work is part of our agreed Milestone 1. Upgrade from JUnit 4 to JUnit 5. This PR migrates the tests located in log4j-jul.

Thank you!

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)

[AlbaHerrerias]

Hi, we are currently blocked and would like your advice. We've found out that the surefire-junit47 provider specified here only executes JUnit 4 tests. We've attempted to change the version and the provider with no luck. Is there another version of this dependency that would set up java.util.logging as required, but will also run JUnit 5 tests? Do you have any pointers for us? Thank you

[ppkarwasz]

@AlbaHerrerias,

The problem with surefire-junit-platform was that either Surefire or JUnit 5 (I don't remember which one) initializes JUL (and therefore Log4j) way before control is transferred to the test class. Therefore this code executes too late:

logging-log4j2/log4j-jul/src/test/java/org/apache/logging/log4j/jul/test/CoreLoggerTest.java

Lines 59 to 62 in 031d4da

	public static void setUpClass() {
	System.setProperty("java.util.logging.manager", LogManager.class.getName());
	System.setProperty(Constants.LOGGER_ADAPTOR_PROPERTY, CoreLoggerAdapter.class.getName());
	}

To workaround that, all the tests must be split into at least 4 Surefire runs, depending on the system properties that they need.
Most test classes require the java.util.logging.manager property to be set (except Log4jBridgeHandlerTest), but some need additional properties.
For example AsyncLoggerThreadsTest additionally needs the log4j2.contextSelector property to be set:

          <execution>
            <id>async-logger-test</id>
            <goals>
              <goal>test</goal>
            </goals>
            <phase>test</phase>
            <configuration>
              <includes>
                <include>**/AsyncLoggerThreadsTest.class</include>
              </includes>
              <!-- Use custom `j.u.l.LogManager` and an asynchronous selector -->
              <systemPropertyVariables>
                <java.util.logging.manager>org.apache.logging.jul.tolog4j.LogManager</java.util.logging.manager>
                <log4j2.contextSelector>org.apache.logging.log4j.core.async.AsyncLoggerContextSelector</log4j2.contextSelector>
              </systemPropertyVariables>
            </configuration>
          </execution>

CoreLoggerTest needs an additional log4j2.julLoggerAdapter system property.

[AlbaHerrerias]

Hello @ppkarwasz , thank you for your help, it unblocked me.

[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]

@AlbaHerrerias,

LGTM, thanks!

[AlbaHerrerias]

Hello @ppkarwasz. I wanted to ask if this refactor needs to be ported to main. Previously, your team has been handling the porting, and I was wondering if you plan to continue doing so for this and the other modules we've refactored that are not yet in main. Thank you! 🙏

[ppkarwasz]

Previously, your team has been handling the porting, and I was wondering if you plan to continue doing so for this and the other modules we've refactored that are not yet in main. Thank you! 🙏

I have the impression that you did all the ports to main (of course for modules that still exist in main). The version of log4j-jul in main is strongly amputated, so no need to migrate this one.

[AlbaHerrerias]

@ppkarwasz
They were made by @vy 🙇

I've compiled a small list with our changes:

PR against 2.x	Ported to main
log4j-jdbc-dbcp2	Yes, done by vy
log4j-jpl	Yes, done by vy
log4j-to-slf4j	No need
log4j-slf4j-impl	No need
log4j-slf4j2-impl	No need
log4j-jul	No need
log4j-jpa	No need
log4j-jakarta-smtp	Does not look it is in main
log4j-taglib	Does not look it is in main
log4j-1.2-api	Does not look it is in main
log4j-api-test (not finished, we need assistance)	Does not look it is in main
log4j-osgi-test
log4j-core-test (not merged)
log4j-iostreams (not merged)

Am I correct in understanding that three modules require porting? (log4j-osgi-test, log4j-core-test, log4j-iostreams). Would you prefer to handle the porting directly, or would you like us to open the PRs against main?

Please note this PR #3221 was related to the migration but not done by us. If I'm not mistaken this is not in main either.

Thank you

[ppkarwasz]

Am I correct in understanding that three modules require porting? (log4j-osgi-test, log4j-core-test, log4j-iostreams). Would you prefer to handle the porting directly, or would you like us to open the PRs against main?

There might be a lot of differences in log4j-core-test between 2.x and main, so please make a separate PR for main if you can. log4j-iostreams shouldn't event be in main and I can port log4j-osgi-test myself.

Please note this PR #3221 was related to the migration but not done by us. If I'm not mistaken this is not in main either.

Thanks for the remark, we didn't notice that, sorry. We'll double-check that PR to see if it contains independent work or is just a squash of all your PRs.

[AlbaHerrerias]

There might be a lot of differences in log4j-core-test between 2.x and main, so please make a separate PR for main if you can. log4j-iostreams shouldn't event be in main and I can port log4j-osgi-test myself.

Thank you. I've incorporated the applicable changes from log4j-core-test into main in this PR.

Thanks for the remark, we didn't notice that, sorry. We'll double-check that PR to see if it contains independent work or is just a squash of all your PRs.

It contains independent work, I don't think it include our changes