Fix MRI Ruby vs. JRuby XML child namespace output differences

[johnnyshields]

Fixes #3455

[johnnyshields]

@flavorjones please approve CI, thanks!

[flavorjones]

I'm not opposed to this approach. I'm wondering if the namespace stack should be managed in the getAttrsAndNamespaces() function, though, since that's already managing one namespace stack (for canonicalized output). WDYT?

[johnnyshields]

@flavorjones I think you're right, I'll look more into getAttrsAndNamespaces tomorrow

[flavorjones]

Thank you so much for diving in and drafting this pull request! I sincerely wish there were more folks like you, who are willing to contribute to the JRuby implementation. ❤️

[johnnyshields]

@flavorjones code is ready for a review. What is the best way to test this? Are there instructions on how to build JRuby locally?

[flavorjones]

@johnnyshields Existing "how to contribute" docs are at https://github.com/sparklemotion/nokogiri/blob/main/CONTRIBUTING.md

but the TLDR is bundle install && bundle exec rake compile test

[johnnyshields]

@flavorjones This is ready for final review.

While testing I found two separate issue unrelated to this PR:

• [bug] JRuby: reparenting a node does not apply the parent's default namespace #3457
• [bug] CRuby namespace shadowing bug #3458

[flavorjones]

Thank you for the thorough test coverage! ❤️

[johnnyshields]

@flavorjones all comments are addressed, please check.

[flavorjones]

Looks good, will merge if the test suite passes.

[flavorjones]

Will get this into a bugfix release soon. But first I'd like to see if I can easily fix the other bugs we're finding and get them in, too.

[johnnyshields]

@flavorjones awesome, I really appreciate it!

[flavorjones]

@johnnyshields I really appreciate you digging in and fixing this!

[flavorjones]

Side note: I'm integration testing Nokogiri main against ruby-saml main in the "downstream" workflow (e.g. https://github.com/sparklemotion/nokogiri/actions/runs/13752072852/job/38454295028).

Should I be testing ruby-saml with JRuby as well, do you think? You're obviously finding edge cases that nobody else has in 15+ years so it might be worthwhile ...

[johnnyshields]

@flavorjones yes, please test JRuby and TruffleRuby for RubySaml if possible 🙏

[flavorjones]

See #3465 for CI coverage

[pitbulk]

Great work here!