Installation

$ yarn add --dev eslint eslint-plugin-jest-extended

Note: If you installed ESLint globally then you must also install eslint-plugin-jest-extended globally.

Usage

[!NOTE]

eslint.config.js is supported, though most of the plugin documentation still currently uses .eslintrc syntax.

Refer to the ESLint documentation on the new configuration file format for more.

Add jest-extended to the plugins section of your .eslintrc configuration file. You can omit the eslint-plugin- prefix:

1{
2  "plugins": ["jest-extended"]
3}

Then configure the rules you want to use under the rules section.

1{
2  "rules": {
3    "jest-extended/prefer-to-be-true": "warn",
4    "jest-extended/prefer-to-be-false": "error"
5  }
6}

Shareable configurations

Recommended

This plugin does not export a recommended configuration, as the rules provided by this plugin are about enforcing usage of preferred matchers for particular patterns, rather than helping to prevent bugs & commonly overlooked traps.

All

If you want to enable all rules instead of only some you can do so by adding the all configuration to your .eslintrc config file:

1{
2  "extends": ["plugin:jest-extended/all"]
3}

To enable this configuration with eslint.config.js, use jestExtended.configs['flat/all']:

1const jestExtended = require('eslint-plugin-jest-extended');
2
3module.exports = [
4  {
5    files: [
6      /* glob matching your test files */
7    ],
8    ...jestExtended.configs['flat/all'],
9  },
10];

Note that the all configuration may change in any release and is thus unsuited for installations requiring long-term consistency.

Rules

🔧 Automatically fixable by the --fix CLI option.

Name	Description	🔧
prefer-to-be-array	Suggest using toBeArray()	🔧
prefer-to-be-false	Suggest using toBeFalse()	🔧
prefer-to-be-object	Suggest using toBeObject()	🔧
prefer-to-be-true	Suggest using toBeTrue()	🔧
prefer-to-have-been-called-once	Suggest using toHaveBeenCalledOnce()	🔧

Credit

• eslint-plugin-jest

Related Projects

eslint-plugin-jest

This project aims to provide linting rules to aid in writing tests using jest.

https://github.com/jest-community/eslint-plugin-jest

eslint-plugin-jest-formatting

This project aims to provide formatting rules (auto-fixable where possible) to ensure consistency and readability in jest test suites.

https://github.com/dangreenisrael/eslint-plugin-jest-formatting