jest-mock-extended VS ts-jest

Create a mock of the Repository that you're testing, it's the simplest one and the more cumbersome one, you can use a library like jest-create-mock-instance or jest-mock-extended or ts-auto-mock to create a mock from typings, but you're responsible to implement how it supposes to work.

You can use something like jest-mock-extended or @golevelup/ts-jest to mock it, and whether your interceptor has dependencies or not, can be more complex or simpler how you instance it.

how does this compare to jest-mock-extended?

use ts-jest and set up Paths Re-Map

Jest's out of the box config for TS doesn't do any type checking. You can integrate https://kulshekhar.github.io/ts-jest/ or you can call ‘tsc’ yourself separately

ts-jest has had some strange performance issues and workarounds in the past, though I haven’t used it very recently so it might have fixed those by now.

Since we're working with TypeScript, we can use ts-jest, which conveniently brings Jest along for the ride:

I want to save you from manually copying the snippets one by one, so here is a Gist with the complete test file. This can be easily executed with Jest (or ts-jest for TypeScript).

See the Jest configuration docs to learn more about Jest configuration. ts-jest also has good documentation.

Using @swc/jest to compile code to CommonJS is much faster than babel-jest, ts-jest which have long cold starts when executing tests in a large project.

ts-jest: A transformer for handling TypeScript files.

Anyway, I ran into this exact error this morning setting up Jest for a TS script. I fixed it by just following the getting started instructions for Jest as well as ts-jest.