Primii pași
Install Jest using your favorite package manager:
- npm
- Yarn
- pnpm
npm install --save-dev jest
yarn add --dev jest
pnpm add --save-dev jest
Let's get started by writing a test for a hypothetical function that adds two numbers. First, create a sum.js
file:
function sum(a, b) {
return a + b;
}
module.exports = sum;
Then, create a file named sum.test.js
. This will contain our actual test:
const sum = require('./sum');
test('adds 1 + 2 to equal 3', () => {
expect(sum(1, 2)).toBe(3);
});
Adăugați secțiunea următoare în fișierul vostru package.json
:
{
"scripts": {
"test": "jest"
}
}
Finally, run yarn test
or npm test
and Jest will print this message:
PASS ./sum.test.js
✓ adds 1 + 2 to equal 3 (5ms)
Tocmai ați scris cu succes primul test folosind Jest!
Testul acesta a folosit expect
și toBe
pentru a testa dacă două valori sunt identice. Pentru a afla mai multe lucruri pe care Jest le poate testa, vezi Utilizarea regulilor de potrivire.
Rularea din linia de comandă
You can run Jest directly from the CLI (if it's globally available in your PATH
, e.g. by yarn global add jest
or npm install jest --global
) with a variety of useful options.
Iată cum să executaţi Jest pe fişierele my-test
, folosind config.json
ca fişier de configurare şi afişarea unei notificări native de sistem după rulare:
jest my-test --notify --config=config.json
Dacă doriţi să aflaţi mai multe despre rularea jest
prin linia de comandă, vezi pagina de Opțiuni Jest pentru linia de comandă.
Informații suplimentare
Generate a basic configuration file
Based on your project, Jest will ask you a few questions and will create a basic configuration file with a short description for each option:
jest --init
Folosind Babel
To use Babel, install required dependencies:
- npm
- Yarn
- pnpm
npm install --save-dev babel-jest @babel/core @babel/preset-env
yarn add --dev babel-jest @babel/core @babel/preset-env
pnpm add --save-dev babel-jest @babel/core @babel/preset-env
Configure Babel to target your current version of Node by creating a babel.config.js
file in the root of your project:
module.exports = {
presets: [['@babel/preset-env', {targets: {node: 'current'}}]],
};
The ideal configuration for Babel will depend on your project. See Babel's docs for more details.
Making your Babel config jest-aware
Jest will set process.env.NODE_ENV
to 'test'
if it's not set to something else. You can use that in your configuration to conditionally setup only the compilation needed for Jest, e.g.
module.exports = api => {
const isTest = api.env('test');
// You can use isTest to determine what presets and plugins to use.
return {
// ...
};
};
babel-jest
is automatically installed when installing Jest and will automatically transform files if a babel configuration exists in your project. Pentru a evita acest comportament, aveţi posibilitatea să reiniţializaţi explicit opţiunea de configurare transform
:
module.exports = {
transform: {},
};
Folosind Webpack
Jest poate fi utilizat în proiecte care folosesc webpack pentru gestionarea fișierelor statice, stiluri şi compilare. webpack oferă unele provocări unice față de alte instrumente. Urmați ghidul webpack pentru a începe.
Using Vite
Jest can be used in projects that use vite to serve source code over native ESM to provide some frontend tooling, vite is an opinionated tool and does offer some out-of-the box workflows. Jest is not fully supported by vite due to how the plugin system from vite works, but there are some working examples for first-class jest integration using vite-jest
, since this is not fully supported, you might as well read the limitation of the vite-jest
. Refer to the vite guide to get started.