8344854: Modernize test/jdk/java/net/URLClassLoader/RemoveJar.java

[eirbjo]

Can I get a review of this test-only cleanup/speedup PR which modernizes the test RemoveJar.java.

This test attempts a variety of class loading scenarios on a URLClassLoader and verifies that when the loader is closed, it has released its JAR file (such that it may be deleted on Windows).

Changes in this PR include:

• Converting the test to JUnit 5
• Making it @Parameterized instead of using multiple jtreg runs
• Producing the sample class file using the ClassFile API instead calling out to javac via ToolProvider
• Packaging the JAR using JarOutputStream instead of calling out to the jar tool.
• Adding some code and method comments to support understading of what this test does and why

A nice benefit of this change is that it speeds up the runtime from ~15 seconds to ~1 second on my laptop.

Unfortunately, this test relies on Windows to fail, that is something I plan to look into separately.

Verification: GHA tests pending. (No local Windows dev environment)

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Progress

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Issue

• JDK-8344854: Modernize test/jdk/java/net/URLClassLoader/RemoveJar.java (Enhancement - P4)

Reviewing

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Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/22319/head:pull/22319
$ git checkout pull/22319

Update a local copy of the PR:
$ git checkout pull/22319
$ git pull https://git.openjdk.org/jdk.git pull/22319/head

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$ git pr checkout 22319

View PR using the GUI difftool:
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https://git.openjdk.org/jdk/pull/22319.diff

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[mlbridge]

Webrevs

• 00: Full (b49bc034)

[dfuch]

Hi Eirik, IIRC the cache is global - so I don't think running the test in the same VM will work. I mean, I don't think we will be testing the same thing.

[eirbjo]

Hi Eirik, IIRC the cache is global - so I don't think running the test in the same VM will work. I mean, I don't think we will be testing the same thing.

If the test should fail because of a regression, then yes, the next parameterized run of the test may start with a non-empty cache. I could add an assertEmptyJarFileCaches method to the start of the test execution, this will verify that all test runs starting with a non-empty cache fails.