Preface to this edition

Thank you for picking up this latest version of Everyday Rails Testing with RSpec. It’s been awhile! As always, Rails and RSpec continue to evolve, but are still your best bet for quickly building (and testing) robust, scalable, full-stack web applications. But the biggest change to our field between 2017 (the last time I released a major update) and today is artificial intelligence.

Now, this is not a book about AI. In fact, this is the only time I’ll even mention it. Can you use AI to write your tests? Sure. Can you expect them to be good tests? Sometimes. But how do you tell the good tests apart from the bad?

AI-assisted programming is likely not going away. And whether or not you choose to use new tools like Claude Code or GitHub Copilot in your daily workflow, we all need to keep core skills sharp: Clean, ideomatic code, fundamentals of software design, and test-driven development.

Good tests don’t just prove your software works. Good tests also prove your software is sustainable for the long haul. Understanding how and where to write these tests takes time–and it’s up to you, as the human in the room with your AI agentic programming buddy, to make those tests happen.

It’s an exciting time to be a software developer! I hope Everyday Rails Testing with RSpec inspires you toward thoughtful software design and development.

Aaron Sumner
Saint Louis, MO, USA
September, 2025