Status of this document: in progress
After an evaluation (only available internally) we’ve decided to use BackstopJS for local testing previous to commiting / providing a new release.
The software is taking reference screenshots (currently from the https://db-ui.github.io/core/ environment) for each pattern individually and compares them with screenshots being made on the local environment during the "test-visual-regression-test" npm script is running.
The tests itself aren’t included in the npm test script, as they are both long-running and ressource-hungry, and thatfor shouldn’t get executed within the pipeline (at the moment), as they are mainly meant to get executed by the developer through their work. The files are being stored within the "tests/" folder, which includes both the config as well as screenshots in a subfolder.
BackstopJS is using Chrome Headless to render the tests, which is perfectly in sync with our upcoming browser strategy. And BackstopJS as well supports simple simulated user interactions like hover and click, which we’d like to test as well depending on defined styles for those.