Visual Regression Testing

Catches visual bugs that slip past functional tests by comparing UI screenshots across versions. You'll want this when refactoring CSS, updating dependencies, or maintaining design systems where a one-pixel shift matters. The references cover Playwright, Percy, Chromatic, and BackstopJS with practical examples for handling the annoying bits like dynamic content and animations. The approach is solid: hide timestamps and random data, test multiple viewports, and keep baselines in version control. One thing to know upfront is that you'll need to carefully tune your diff thresholds, because too strict means constant false positives and too loose means missing real bugs. Works best for stable UI components rather than pages with constantly changing content.