Ask HN: How do you achieve high-coverage tests for your SPA UI/UX?

In the backend API world you can get away with doing mostly integration tests and unit tests for the service objects and such. Fairly easy and straightforward.

What's the equivalent approach for the frontend SPA?

It's so easy to write fairly comprehensive tests for a backend API, but how do you do the same for your SPA? What's the most straightforward way to do integration-level testing? What's the best way to quickly cover the look, feel, and states?