What is visual regression testing?

An interesting application for this is also from the perspective of Accessibility. If the web page isn't visually consistent, a lot of users with accessibility tools like screen readers, keyboard navigation etc will have trouble interacting with websites

Visual regression testing is crucial in web development to ensure a consistent user experience across various devices and browsers. It helps detect layout, alignment, color, and functionality discrepancies caused by factors like browser versions and device types. By identifying and addressing these issues early, developers can deliver a polished product that aligns with client expectations and brand identity. This ultimately enhances user satisfaction and trust in the brand.

This comparison can be performed manually or automatically using specialized tools equipped with image processing algorithms. Any visual disparities are identified and highlighted. Differences can be reported in terms of pixels, percentages, or specific regions, and categorized as pass, fail, or warranting attention based on severity and tolerance levels. The developer can review results and decide whether to accept, reject, or disregard the changes, and update the baseline image as needed.

Percy: A cloud-based platform that integrates with various testing frameworks and tools (e.g., Cypress, Jest, Selenium, Storybook). It provides a visual dashboard for reviewing and approving changes. BackstopJS: A node-based tool that utilizes Puppeteer, Chrome Headless, or SlimerJS to capture and compare screenshots. It generates HTML reports with interactive features. Applitools: A cloud-based platform that employs artificial intelligence to compare screenshots and identify visual bugs. It offers a web interface for managing and analyzing results. Wraith: A ruby-based tool that uses PhantomJS or SlimerJS to capture and compare screenshots. It generates a gallery of images with diff overlays.

Also Argos, visual testing for developers with solid Cypress and Playwright integrations. It is a very good alternative to Percy.

Resource Intensiveness: Visual regression testing may require significant computational resources, particularly when handling a large number of pages, scenarios, and variations. This can impact performance and scalability. Time-Consuming: Capturing and comparing screenshots across different browsers, devices, and screen sizes can be time-consuming. This can slow down the testing process, especially for extensive web applications. Maintenance Overhead: Regularly updating baseline images and handling dynamic content can be labor-intensive, especially in projects with frequent UI changes.