I just recently did a website conversion that used vite and took a look at both vitest and playwright.

Ended up going with playwright for the “batteries included” browser support and because we use .Net Core for the backend.

dotnet doesn’t always get the best support from pure JS/TS projects, so it seemed like a reasonable hedge.

I was under the impression that playwright was (a very good) how your code behaves when actually running in a browser testing library, and vitest was a how your code behaves on its own testing library.

But I'd tend to have relatively independent test suites for my frontend model/state layer and the "how it behaves live in a browser" stuff because that way if I'm not currently iterating on my view components I can test the rest of my frontend code changes without having to faff with headless browser instances.

(obviously you'd then want to run both before committing, and again under CI before merge, but still)

Depending on how thin your model/state layer is (and if you have a Sufficiently Rich Backend then it can probably be very thin without that being an issue) your situation may not match mine, of course.

But y'know, free data point, worth exactly what you paid :D