Here is a draft of the contribution guide to JRuby.

See Download and Build JRuby.

Here are the different test commands:

• ant test : runs all JRuby unit tests.
• ant spec-short : runs Rubyspecs for 1.8 and 1.9 in interpreted mode.

• To run a spec separately:

./bin/jruby -S mspec /path/to/spec.rb

• Do not change specs in the JRuby codebase, as they are being updated from https://github.com/rubyspec/rubyspec/. Instead create a PR in the Rubyspecs project.

• Make sure commit comments contain as much information as possible on the intent of the fix, so that PRs can be reviewed more easily.
• Use feature branch if possible (?)
• Keep big formatting changes in separate commits or PR to make review easier.
• See the GitHub Guide for more details.

See the JRuby Style Guide.