The Secret to Safe Continuous Deployment
Why Stack Overflow recommends it
Stack Overflow users link it when someone asks how to automate look-and-feel or screenshot comparison testing, since it shows perceptual diffs used in a real deployment pipeline.
Recommended by 2 people across 2 different months, 2013 to 2017.
What it is
A Google Developers Live talk by Bret Slatkin on the Google Consumer Surveys team, where code goes live in production eight minutes after commit. He covers a year of experience with continuous deployment, what went wrong, and how screenshot-based visual (perceptual) diffs between releases made it safe.
What people said
Strong rec MariusVolkhart · 2013-09 · Stack Overflow · on “How can we test external css file content with selenium UI verification”
If you want to really dig into this, there's an excellent [this video] and a good InfoQ article [LINK] about how Google uses pdiffs.
Recommends messivanio · 2013-07 · Stack Overflow · on “Is there a way to automate 'look and feel' testing of a web page?”
There is a YouTube video with a great approach for the problem: The Secret to Safe Continuous Deployment [this video] from Google Developers Live. In the video Breett Slatkin [LINK] teach us how to use visual diffs to make 'look and feel' testing. I hope this can help you.
Cites Luke Francl · 2017-08 · Stack Overflow · on “How do I compare screenshots taken in pyscreenshot with saved screenshots?”
You might be interested in using a perceptual diff tool which will let you quickly identify differences in the screenshots. imgdiff [LINK] is a library that wraps a tool for this in Python. A simple version can probably be implemented with PIL's ImageChop , as in this answer [LINK] : import Image import ImageChops im1 = Image.open("splash.png") im2 = Image.open("splash2.png") diff = ImageChops.difference(im2, im1) For more on perceptual diffing, check out Bret Slatkin's talk about using it for safe continuous deployment [this video] .