CODEWITHSUNDEEP
javascriptjestjses6-modules
guy mograbi
guy mograbi

Reputation: 28728

How can I import Jest?

I would like to get rid of global variables in my Jest test code. Specifically describe, it, and expect:

describe('Welcome (Snapshot)', () => {
  it('Welcome renders hello world', () => {
    // ...
  });
});

So I tried to add:

import { describe, it } from 'jest';

and

import jest from 'jest';

jest.describe('Welcome (Snapshot)', () => {
  jest.it('Welcome renders hello world', () => {
    // ...
  });
});

And other variation but it's not working.

How can I get my Jest test code working without globals?

Upvotes: 52

Views: 52331

Answers (4)

agilgur5
agilgur5

Reputation: 837

Update: As of Jest 26, the @jest/globals package can be used to import Jest functions:

import { describe, it, expect } from '@jest/globals'

Jest 26.5 further added the injectGlobals config that you can set to false to disable globals in your test files:

// jest.config.js
/** @type {import('jest').Config} */
const config = {
  injectGlobals: false,
};

module.exports = config;

For versions of Jest older than 26, you can use the jest-without-globals package as described below:

I similarly don't like using or relying on globals, and after copy/pasting various workarounds in different projects, I decided to create jest-without-globals as a very tiny wrapper to support importing Jest's features.

Per the Usage docs, it's straightforward to use:

import { describe, it, expect } from 'jest-without-globals'

describe('describe should create a section', () => {
  it('it should checkmark', () => {
    expect('').toBe('')
   })
})

All of the functions available in Jest's API, as well as jest and expect, can be imported from jest-without-globals.

Using jest-without-globals, I don't need to copy/paste workarounds anymore and don't need to configure settings like ESLint's jest environment, it just works as a simple import.
It's also written in TypeScript so you have typings out-of-the-box and it's fully tested to ensure it keeps working correctly.

Upvotes: 6

derekbaker783
derekbaker783

Reputation: 9610

Try the code below:

import {describe, expect, it} from '@jest/globals'

if you prefer explicit imports, you can do import {describe, expect, test} from '@jest/globals'.

Source https://jestjs.io/docs/en/api

Upvotes: 35

Alejandro Garcia Anglada
Alejandro Garcia Anglada

Reputation: 2403

The simplest solution for this is adding jest: true to your env configuration in ESLint, like so:

"env": {
  "browser": true,
  "node": true,
  "jasmine": true,
  "jest": true,
  "es6": true
},

Upvotes: 33

guy mograbi
guy mograbi

Reputation: 28728

After I realized Jest is running in Node.js, it realized I could do this:

let { describe, it } = global;

It is not perfect, but one step closer... now I don't need to configure my linter with global variables any more.

Upvotes: 25

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