At Codeception we are glad to receive contributions and patches from the community. There are a few guidelines that we need contributors to follow so that we can have a chance of keeping on top of things.
Please check the guide for sending your contributions with Github at https://github.com/Codeception/Codeception/wiki/Git-workflow-for-Codeception-contributors
All contributions must follow PSR-2 coding standard.
Bugfixes should be sent to to current stable branch, which is the same as major version number.
Breaking features and major improvements should be sent into master. When you send PRs to master, they will be added to release cycle only when the next stable branch is started.
Check the tests/README.md to learn how to run and write internal tests. We encourage you to write a test for a patch you are implementing. If this doesn't seem possible, such PRs are stil valid and can be accepted.
We also encourage to submit bug reports with a failing test or test environment (3rd party repo with Codeception installation) with demonstration of a failure. That makes easier to us to find the cause and fix it.
If you want to contribute documentation to the guides you are asked to send your changes to the /docs/ folder: https://github.com/Codeception/Codeception/tree/2.2/docs. Theses files are the source for the codeception website guides: http://codeception.com/docs/01-Introduction. Remind to send your documentation improvements to the right "repository branch" depending on the Codeception version you are working with: 2.2, master,...
The documentation for each module is directly generated from the corresponding docblock which can be found in each module (src/Codeception/Module/*.php).