RFR: 8378111: Migrate java/util/jar tests to JUnit [v2]

[Eirik Bjørsnøs]

On Fri, 20 Feb 2026 18:42:35 GMT, Justin Lu <jlu at openjdk.org> wrote:

> I pulled `TestJarExtra` into its own test file which gets rid of the manual instance handling and is cleaner.

Thanks for making this cleaner!

Ideally I would like to see these broken up into self-contained tests. The inheritance here just seems like implementation sharing without any real benefits. It just makes it harder to tell where things come from and prevents the tests from "telling a story". 

But yeah, that's probably outside of this JUnit conversion PR; I think you've done a good job already!

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PR Review Comment: https://git.openjdk.org/jdk/pull/29828#discussion_r2834745684