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Just realized Vitest now has built in support for testing TypeScript types. How? It includes expect-type now by default. Handy. Example:

13/5/25, 4:15 pm1 repost7 likes

I don't quite get the benefit of this compared to typing the function and converting the file to typescript?

Ah I see, it's for libraries that want to avoid writing the library in typescript.

github.com/vitest-dev/v...

github.com[RFC] Testing types with expectTypeOf and assertType · Issue #1954 · vitest-dev/vitestClear and concise description of the problem Currently users have to come up with their own solutions to test types. Fo example, Vue defines a set of small utils: export function expectType<T>(valu...