msw VS jest

However, I discovered a great combination that transformed my API call testing in TypeScript: Vitest and Mock Service Worker (MSW). Their well-crafted design makes them incredibly easy to use, enhancing the overall testing experience.

While mocks are effective, they require modifying the component's internal logic or mocking global functions like fetch. This can become cumbersome for complex components with numerous API interactions. Here's where MSW shines.

> For those wondering what the use case is, you must not have tried it. It does take work to set up (with each version that's less), but it can be very nice to test in isolation esp in cases where a component is under a login, the 4th page of a 10 page form, etc. Also obviously if you're working on a component library that ships without an app, Storybook can be your development and/or demo app.

I have worked with storybook extensively over the past couple of years and my team is moving away from it in favour of MSW (https://mswjs.io).

For "4th page of a 10 page form" during the development there's hot reloading which is really stable nowadays and haven't failed me, although I understand that some setups are old and it might be easier to configure Storybook than good hot reloading.

I'm not entirely sure about the testing part of it and I'd be grateful if you could elaborate. I haven't felt the need for some special setup with SB because for unit tests, I can test a deeply nested component separately. For E2E tests, I usually test the whole form.

I agree on the component library part, this is probably the only use case where Storybook is 100% justified, but I'm unconvinced about the

Additionally, thank you to all our community launch partners across the frontend ecosystem for helping us bring Storybook 8 to the world! Thanks to Chromatic, Figma, ViteConf, Omlet, DivRiots, story.to.design, StackBlitz, UXpin, Nx, Mock Service Worker, Anima, Zeplin, zeroheight, kickstartDS, and Kendo UI.

similar with msw.js, but fully automated

they could be network mocks (use msw)

With orval, we can also integrate the API client in our unit tests. Orval provides first class support for mocking through the (Mock Service Worker)[https://mswjs.io/] library, and it can automatically generate the MSW handlers for testing server.

Consider a hypothetical scenario where data from a list of companies within an ERP needs to be retrieved. As a personal recommendation, leverage tools like MSW for top-level mocks, which can significantly enhance the testing process.

GitHub | Website

Jest

you have selected a testing framework. In my case, it's Jest with Supertest

Jest, created and maintained by Facebook, is a JavaScript testing framework with a focus on simplicity. It is often recognized for its zero-configuration setup and seamless integration, especially with React applications, making it a favored choice for developers in both small-scale projects and large enterprise applications.

Jest (https://jestjs.io/)

console.error Jest encountered an unexpected token Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax. Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration. By default "node\_modules" folder is ignored by transformers. Here's what you can do: • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it. • If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript • To have some of your "node\_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config. • If you need a custom transformation specify a "transform" option in your config. • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option. You'll find more details and examples of these config options in the docs: https://jestjs.io/docs/configuration For information about custom transformations, see: https://jestjs.io/docs/code-transformation

Note: I will be using Jest as testing framework throughout the examples.

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!

Jest has long been my favorite got to test runner when it comes to UI unit and integration testing. With tools like React Testing Library (Testing Library framework for React) you get the benefit of very easy to write and maintain tests, as well as a quick and efficient way to run our tests.

Jest is a well-regarded JavaScript testing framework primarily designed for React applications, although its utility extends to projects using Babel, JavaScript, Node, Angular, and Vue. Created by Facebook, Jest emphasizes ensuring the correctness of JavaScript codebases. It allows developers to write tests with a familiar, feature-rich API, making the testing process swift and enjoyable​​.