Episode 14: Diffy and Visual Regression Testing with Yuri Gerasymov

This week, Oliver discusses visual regression testing and Diffy with Yuri Gerasymov.

Key points

  • What is visual regression testing?
  • How do you deal with false positives?
  • Different use cases for visual regression testing.
  • Automatic updates.
  • Scheduling content.
  • Visual regression testing in CI.
  • Diffy in WordPress.
  • What's a baseline?
  • Initial setup and onboarding feedback.
  • Testing dark mode?
  • Component testing with Storybook and Fractal?
  • Testing local environments.
  • Testing as authenticated users.
  • The roadmap for Diffy.


  • We help development teams to have less visual bugs in their website. We take screenshots of the pages and compare them so you can see what changed and how. (YG)
  • We built tools for you to mock the content. You provide selectors for the elements with the content of the article and we'll replace it with lorem ipsum text so it will be exactly the same across multiple environments. (YG)
  • I can still write an assertion to check the text is on the page or not, but it won't confirm it's in the correct place. (OD)
  • Having a tool checking for changes on a regular basis instead of only after a deployment would be very useful. (OD)
  • So, you could have a tool like Violinst automatically creating pull requests and Diffy checking those PRs, so the two could work together? (OD)
  • With visual testing, it's very easy to get started. (YG)
  • Visual testing is great for showing your client your work. (YG)

About me

Picture of Oliver

I'm an Acquia-certified Drupal Triple Expert with 17 years of experience, an open-source software maintainer and Drupal core contributor, public speaker, live streamer, and host of the Beyond Blocks podcast.