Fedora is modularizing. But what does it mean to make disparate modules work well together? Cockpit is a fast paced project that touches many other technologies and has evolved over the years into a system that does exactly this. I want to share how Cockpit survives modularization, distribution releases, changing APIs and new features by testing against real operating systems before code is even merged, released or packaged. You'll see how we integrate, how the testing is composable and upstream & testing framework agnostic. We show how to focus on the goal - deliver software that works for users.