genType VS rescript-jest

I don't really use ts-belt to be certain, but by looking at the source, it seems that it's using genType, which can generate TS types from ReScript values, and that makes interop work really well.

They discuss this in their docs.

https://rescript-lang.org/docs/manual/latest/introduction#di...

Seems like a type system for Javascript, built with a differing set of opinions than Typescript.

Looks like they also offer some form of TS interop:

https://rescript-lang.org/docs/gentype/latest/introduction

TS Belt has been built with ReScript (and its Belt stdlib). ReScript generates highly performant JavaScript code, and with genType it also automatically generates TypeScript types. Moreover, I've added a few codemods to the building process to provide even more code optimizations and cleaner TypeScript signatures.

To interoperate with TypeScript with proper type information you’ll use third-party genType. Add it as a devDependency and annotate the module export you want to generate with @genType (in previous versions you’d surround annotations with square brackets).

Another popular option is to use bindings for Jest. However, in my opinion, Jest is a monstrous combine that is slow, has a hacky mock system, bad ESM support, and purely tries to mimic DOM API with JSDOM. AVA literally doesn't have any of these. Also, the available Jest bindings don't allow doing multiple assertions per test, which is often useful to me.

In order to write tests in ReScript, and thus test your code directly, you can use bs-jest, which provides ReScript bindings to Jest. If you prefer, you can also use the slightly less mature bs-mocha. You can also test the generated JavaScript or TypeScript files with no extra configuration.