@types/jest 29.5.12

The @types/jest is a valuable npm package that provides TypeScript definition for Jest. Jest is a popular JavaScript testing framework, and this package enables it to work seamlessly with TypeScript. It includes well-defined type definitions which ensure type safety when writing tests in TypeScript while leveraging Jest's robust testing capabilities. The TypeScript definition allows your IDE to provide intellisense and easier code navigation, which ultimately improve your coding experience.

Using @types/jest is straightforward, first ensure you have already installed Jest and TypeScript in your project setup. Then, you run the following command in your terminal:

npm install --save-dev @types/jest

or

yarn add --dev @types/jest

After installation, you can create your tests as you would while writing them in TypeScript. As an example, here is how a test using Jest and TypeScript might look:

import { sum } from './sum';

test('adds 1 + 2 to equal 3', () => {
    expect(sum(1, 2)).toBe(3);
});

In the code snippet above, the function sum can enjoy TypeScript intellisense and won't throw TypeScript errors if properly used, thanks to @types/jest.

The documentation for @types/jest can primarily be found on DefinitelyTyped's GitHub repository at https://github.com/DefinitelyTyped/DefinitelyTyped. However, being a type definition, most of the usage revolves around the usage of Jest itself, so Jest's official documentation at https://jestjs.io/docs/en/getting-started is also an indispensable resource.