docs(README): Add information about visual regression tests
- [Development](#development)
- [Prerequisites](#prerequisites)
- [Installation](#installation)
+ - [Testing](#testing)
- [Technical Notes](#technical-notes)
## Quick Start
@@ -79,6 +80,20 @@ npm install
npm run dev
```
+### Testing
+
+We use visual regression testing powered by [Sauce Labs](https://saucelabs.com), [Argos](https://www.argos-ci.com), and [WebdriverIO](https://webdriver.io).
+The themes are built, rendered in a browser running on Sauce Labs, and screenshots taken and compared by Argos.
+
+To run these tests locally, run `npm run test`.
+By default Webdriver will try to run the tests using Chrome, but you can switch to Firefox by setting an `TEST_BROWSER=firefox` environment variable.
+
+When testing locally, there are three screenshot folders to be aware of inside the `test/screenshots` directory.
+
+- `reference`: These are the baseline screenshots. To generate them, make sure your Git branch is free of any changes, and run `npm test`.
+- `local`: These are screenshots generated by Webdriver tests, and will be compared to those found in the `reference` directory.
+- `diff`: If any discrepancies are found between the `reference` and `local` screenshots, the differences will be highlighted and saved to this directory.
+
## Technical Notes
We use [Parcel](https://parceljs.org) to compile this module. One of the
