jest run tests code example

Example 1: how to install jest

npm install --save-dev jest

// Yarn
yarn add --dev jest

Example 2: npm run test:coverage command in jest

npm test -- --coverage

Example 3: jest run specific test

From the command line, use the --testNamePattern or -t flag:

jest -t 'fix-order-test'
This will only run tests that match the test name pattern you provide. It's in the Jest documentation.

Another way is to run tests in watch mode, jest --watch, and then press P to filter the tests by typing the test file name or T to run a single test name.

If you have an it inside of a describe block, you have to run

jest -t '<describeString> <itString>'

Example 4: what is jest

Jest is a JavaScript testing framework maintained by Facebook, Inc. with a
focus on simplicity.

It works with projects using: Babel, TypeScript, Node.js, React, Angular and
Vue.js.

It aims to work out of the box and config free.