Here's a few ideas on testing web apps: 1. The internal pure data representation. If you're using some state management like redux or xstate then you can just

Here's a few ideas on testing web apps: 1. The internal pure data representation. If you're using some state management like redux or xstate then you can just cache the state on changes and run tests as-is (e.g. running the tests would be sending events and then checking that the state is what you expect it to be). 2. The page itself. Tools like Selenium and Cypress will allow you to easily inspect and run tests against the DOM state (e.g. running the tests would be emulating interactions with the page and checking that the properties of elements are what you expect them to be) 3. Checking the virtual dom (or other middleware). For example, with React, you can "get at" its internal data (at least the level you need) via a testing framework like Enzyme. 4. If your app uses webgl context or is simply too hard to test on any of the above "pure data" levels, you need some sort of image recognition to compare pixels. I doubt this is going to be _perfectly_ testable but you can try your hand at Sikuli or roll your own with OpenCV