The Hue project gladly welcomes improvements!
This document contains instructions on how to get involved. In any case, feel free to ask questions.
Here is some inspiration:
Here is a good example of Pull request with code and unit test with mocks.
Have a look at how to quick build.
It is flexible but Github Pull request are handy.
Just post the pull request and reviewers will start from there. The CI will run a basic set of tests for you.
A general rule is to follow the on-going style of the code context.
See how to automatically run the tests via CircleCi by pushing to a branch or opening-up a pull request.