At New Relic we welcome community code contributions to the Ruby Agent, and have taken effort to make this process easy for both contributors and our development team.
When contributing keep in mind that the agent runs in a wide variety of ruby language implementations (e.g. 1.8.6, 1.8.7, 1.9.x, jruby, etc.) as well as a wide variety of application environments (e.g. rails, sinatra, roll-your-own, etc., etc.)
Because of this we need to be more defensive in our coding practices than most
projects. Syntax must be compatible with all supported ruby implementations
(e.g. no 1.9 specific hash syntax) and we can't assume the presence of any
specific libraries such as ActiveSupport.
The agent includes a suite of unit tests which should be used to verify your changes don't break existing functionality.
Running the test suite is simple. Just invoke:
bundle
bundle exec rake
This will run the unit tests in standalone mode, bootstrapping a basic Rails 3.2 environment for the agent to instrument then executing the test suite.
These tests are setup to run automatically in travis-ci under several Ruby implementations. When you've pushed your changes to github you can confirm that the travis-ci build passes for your fork of the codebase.
Additionally, our own CI jobs runs these tests under multiple versions of Rails to verify compatibility.
For most contributions it is strongly recommended to add additional tests which exercise your changes.
This helps us efficiently incorporate your changes into our mainline codebase and provides a safeguard that your change won't be broken by future development.
There are some rare cases where code changes do not result in changed functionality (e.g. a performance optimization) and new tests are not required. In general, including tests with your pull request dramatically increases the chances it will be accepted.