eslint-plugin-jest-extended

3.0.1 verified Sat Apr 25 auth: no javascript

ESLint plugin providing rules for Jest Extended matchers, version 3.0.1 (latest stable). Released under the jest-community organization, this plugin offers rules like prefer-to-be-true, prefer-to-be-false, prefer-to-be-array, prefer-to-be-object, and prefer-to-have-been-called-once, all auto-fixable. It supports ESLint 7/8/9, Node >=16.10, and flat config. Differentiates from eslint-plugin-jest by focusing on jest-extended matchers rather than general Jest best practices. Release cadence: occasional major/minor updates with breaking changes tied to Node and ESLint version support.

Common errors

error Error: Cannot find module 'eslint-plugin-jest-extended' ↓

cause Package not installed or missing from node_modules

fix

Run npm install --save-dev eslint-plugin-jest-extended

error Configuration for rule "jest-extended/prefer-to-be-true" is invalid ↓

cause Typo in rule name or using 'jest-extended' as a rule without proper plugin declaration

fix

Ensure plugin is listed in 'plugins': ['jest-extended'] and rule names are correct (e.g., 'jest-extended/prefer-to-be-true')

error ESLint couldn't find the plugin "eslint-plugin-jest-extended". ↓

cause Plugin not installed, or ESLint is global and plugin is local

fix

Install plugin locally or globally to match ESLint installation: npm install --save-dev eslint-plugin-jest-extended or npm install -g eslint-plugin-jest-extended

error TypeError: Cannot read properties of undefined (reading 'flat/all') ↓

cause Using an older version before flat config support was added (v2.3.0)

fix

Upgrade to v2.3.0 or later, or use .eslintrc syntax

Warnings

breaking v3.0.0 drops support for Node v14 and Node v18 versions below 18.12.0 ↓

fix Upgrade Node to ^16.10.0 || ^18.12.0 || >=20.0.0

breaking v3.0.0 raises minimum peer dependency for @typescript-eslint/utils to v6; v7 and v8 also supported. ↓

fix If using TypeScript-related ESLint configs, ensure @typescript-eslint/utils is at least v6.

gotcha The 'all' config may change in any release and is not suitable for long-term consistency. ↓

fix Pin to specific rules instead of using 'all' configuration for stable behavior.

deprecated v2.x is no longer maintained; upgrades to v3 are recommended. ↓

fix Upgrade to v3.0.1 with `npm install eslint-plugin-jest-extended@latest`.

Install

npm install eslint-plugin-jest-extended

yarn add eslint-plugin-jest-extended

pnpm add eslint-plugin-jest-extended

Imports

plugin

wrong

import jestExtended from 'eslint-plugin-jest-extended';

correct

const jestExtended = require('eslint-plugin-jest-extended');

The package is CommonJS-only; ESM import may fail without a bundler that handles CJS interop.

configs
wrong
```
jestExtended.configs.all
```
correct
```
jestExtended.configs['flat/all']
```
Flat configs are accessed via string keys like 'flat/all'; the 'flat/all' key is used in eslint.config.js. The 'all' key exists but is for .eslintrc extended syntax.
rules
wrong
```
"jest-extended/prefer-to-be-true": "error"
```
correct
```
"jest-extended/prefer-to-be-true": "warn"
```
Rule names are prefixed with 'jest-extended/' when configuring in .eslintrc under rules section.

Quickstart

Shows both .eslintrc and flat config usage to enable plugin and configure rules.

// .eslintrc.json
{
  "plugins": ["jest-extended"],
  "rules": {
    "jest-extended/prefer-to-be-true": "warn",
    "jest-extended/prefer-to-be-false": "error"
  }
}

// eslint.config.js
const jestExtended = require('eslint-plugin-jest-extended');

module.exports = [
  {
    files: ['**/*.test.js', '**/*.spec.js'],
    ...jestExtended.configs['flat/all'],
    rules: {
      'jest-extended/prefer-to-be-true': 'warn',
    },
  },
];