We would value any pull requests that help us fulfill Cuppa's mission. Check out the list of open issues. We're especially looking for help with the help wanted issues.
We want Cuppa to become the de facto testing framework for Java. Cuppa's goal is to make the development of tests fast and fun. It is written for developers and as such must always focus on developer experience first. Cuppa should be as simple as possible while being fully extensible, allowing others to build great tools on top of it.
Does that sound like your cup of tea? If so, great, fork away!