Unit testing is mostly a solved problem, but how do you write tests for the visual side of your app—the part that your users actually see and interact with? How do you stop visual bugs from reaching your users? We will dive deep into visual regression testing, a fast-growing technique for testing apps pixel-by-pixel. We will integrate perceptual diffs in Rails feature specs, and learn how to visually test even complex UI states. We will show tools and techniques for continuous visual integration on every commit, and learn how to introduce team visual reviews right alongside code reviews.