Contributions are most welcome!
Keep your lines below 100 characters so they show up nicely on Github.
Make sure you describe the new feature, or bugfix, or whatever. Please do not use commit messages
like "various tweaks". Ideally, git log reads like a changelog.
The latter can be helped by amending existing commits. Instead of 50 little commits with very detailed messages, consider squashing commits into 1 or 2 separate commits with meaningful messages.
Using git rebase -i can help retain a meaningful commit history.
We use PHPCS to check coding standards. There's a custom set of rules in phpcs.xml. It's a lot
more forgiving than other styles out there, so it shouldn't be that hard to comply.
See also our PHP CodeSniffer wiki page for a way to automatically check coding standards before committing your work.
Always include tests that confirm the new feature works as intended.
Obviously running the test suite also confirms you haven't broken any existing functionality.
Specifically, when fixing a bug, try to add a test that describes the exact scenario you have now fixed. I like a test suite that documents failures from the past, to make sure they won't be re-introduced in future releases.
Run the tests with phpunit from the project root.