Automation of GUI testing using visual regression testing - Audun Wigum Arbo - NDC Oslo 2023

Have you ever spent hours on perfecting a UI, only to have it break in subtle ways by later regressions? Small details like positioning, borders and colours might get changed in subtle ways, and gradually get out of control. With automated visual regression testing, you’ll catch all these kinds of issues, reducing tedious and error-prone manual testing.

What a participant will get out of my presentation:

* Get to know about what visual regression testing is.
* Understand the basics through a hands-on demonstration using Playwright's web browser-based end-to-end tests, and Percy.
* When to use these kinds of tests; where it saves time and improves software robustness.

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[Keisuki]

I've worked in a large company, on a large system, which used exactly this technique. It made my life truly horrible.

As the developer setting up your website for the first time, you may have a lot of respect for the visual tests, be careful to limit animation, lazy loading, randomness, and anything that can cause variance in the tests. That doesn't mean that in a few years, things will still be so peachy.

Our release process involved the developer manually checking like 2000 images, approving small changes where the title had somehow been rendered 1 pixel to the left of where it was last time, or the lazy loaded images had loaded on one but not the other, or where dates have changed, or where a carousel was caught mid turn animation.

I would have loved to have released our code multiple times a week, but this horrible process that management wouldn't let us change meant that every release was soul-crushing, so we only released once or twice a month. Slower releases mean it's slower to get bug fixes out, more stuff is batched up, and big disasters are more likely to happen.

So I say: Visual testing may work well for you now, but in a few years, as new people join the project who know less, it'll degrade to the point of effectively destroying your team.