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Talk on visual regression testing at c't webdev 2020

February 06, 2020

In the spring of last year, I wrote two blog posts on visual regression testing on the “Know-how from the RRZK Cologne” blog (where I’m employed). There I described how the Puppeteer Headless Browser API together with the Image comparison library ResembleJS can be used to roll your own Visual Regression Testing tool. I was therefore very excited when I was invited to speak at the c’t webdev 2020 conference on the topic. This is how my first presentation at a technical conference came about…

The slides can be clicked through directly in German and English (I gave the talk in German). The two small demos can be grabbed from Github.

If there are any questions or comments I would like to hear from you (@moritzvd or

The abstract for the talk:

The webmaster team of the Regional Computer Center (RRZK) of the University of Cologne provides the various university institutions with centrally administered TYPO3 CMS systems. On hundreds of domains, the university thus presents itself on the web in all its diversity. The systems are of course continuously maintained and updated. However, every change or correction carries the risk of side effects and errors at an unexpected place in the system. Regression tests have the task of preventing this. Since last year, RRZK has been using visual end-to-end tests to test the websites for updates from the perspective of end-users. Based on the situation at the University of Cologne, the presentation will introduce the tools and libraries used at the RRZK and show that even classic CMS systems can be continuously tested with modern means (NodeJS, Headless Chrome via Puppeteer and ResembleJS).

I'm starting this blog in order to share and learn new fun stuff on system adminstration and full stack web development. You can reach me via e-mail.