wordpress/tests/visual-regression/README.md

# Visual Regression Tests in WordPress Core

These tests make use of Jest and Puppeteer, with a setup very similar to that of the e2e tests, together with [jest-image-snapshot](https://github.com/americanexpress/jest-image-snapshot) for generating the visual diffs.

## How to Run the Tests Locally

1. Check out trunk.
2. Run `npm run test:visual` to generate some base snapshots.
3. Check out the feature branch to be tested.
4. Run `npm run test:visual` again. If any tests fail, the diff images can be found in `tests/visual-regression/specs/__image_snapshots__/__diff_output__`.
Build/Test Tools: Introduce local visual regression testing. Adds the ability to ''locally'' run visual regression testing for wp-admin pages via `npm run test:visual`. Snapshots are stored on contributors' local machines. Note: Wiring to the CI is not included. Why? The challenges for the CI are storage of the artifacts and unreliability of testing these across different environments. This commit is a first step towards visual regression testing. Running it locally provides a learning opportunity which could help to craft how to build it into the automated CI process. Props isabel_brison, andraganescu, azaozz, danfarrow, desrosj, hellofromTonya, justinahinon, netweb, talldanwp. Fixes #49606. git-svn-id: https://develop.svn.wordpress.org/trunk@51989 602fd350-edb4-49c9-b593-d223f7449a82 2021-11-02 21:03:10 +00:00			`# Visual Regression Tests in WordPress Core`

			`These tests make use of Jest and Puppeteer, with a setup very similar to that of the e2e tests, together with [jest-image-snapshot](https://github.com/americanexpress/jest-image-snapshot) for generating the visual diffs.`

			`## How to Run the Tests Locally`

			`1. Check out trunk.`
			2. Run `npm run test:visual` to generate some base snapshots.
			`3. Check out the feature branch to be tested.`
			4. Run `npm run test:visual` again. If any tests fail, the diff images can be found in `tests/visual-regression/specs/__image_snapshots__/__diff_output__`.