ts-jest VS mocha

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.

Using something like Vitest, Jest, or Mocha didn't work because:

MochaJS is a feature-rich JavaScript test framework running on Node.js, making it a popular choice for both backend and frontend testing. It's known for its flexibility and straightforward syntax, allowing for asynchronous testing and the use of any assertion library.

We use Jest Framework for testing. Jest is not a dogma, and, of course, in its place can be any other test runner, such as Mocha or Ava. Let's focus on tests. I'll provide a short example because I don’t want to waste your time. You can find the full version here. It's crucial to read the comments in the code below. Let's go!

JavaScript Popular tools for testing: Mocha, Jasmine, Unit JS, Jest

To execute your tests, you can create test scripts using popular testing frameworks like Mocha, Jasmine, or Jest. These frameworks provide a structured way to organize and run your tests, report results, and handle assertions.

⚗️ Mocha and Chai for testing

Testing frameworks like Jest, Mocha, and Jasmine are crucial for software development, ensuring code reliability and correctness. They offer features like test suites, test cases, assertions, and asynchronous testing support.