@lcooper/eslint-config-jest

An ESlint shareable flat config for Jest testing environments.

Installation

The peer dependency eslint must be installed alongside this package.

install with npm:

npm install -D eslint @lcooper/eslint-config-jest

install with yarn:

yarn add -D eslint @lcooper/eslint-config-jest

Note: This project requires Eslint version >=8.56, and NodeJS version ^18.18.0 || >=20.0.0.

Usage

Add an eslint.config.js config file to your project's root directory. This config is meant to be used in addition to the base @lcooper/eslint-config config or @lcooper/eslint-config-typescript config.

Note: this package exports a single flat config object, so no need for the ... spread syntax when using it.

import baseConfig from '@lcooper/eslint-config';
import jestConfig from '@lcooper/eslint-config-jest';

export default [
    ...baseConfig,
    jestConfig,
];

If your project does not specify "type": "module" in its package.json file, then eslint.config.js must be in CommonJS format:

const baseConfig = require('@lcooper/eslint-config'),
    jestConfig = require('@lcooper/eslint-config-jest');

module.exports = [
    ...baseConfig,
    jestConfig,
];

This project is no longer compatable with the legacy eslintrc format, and requires you use the flat config format. Check out this page for more details about migrating from the eslintrc format to the flat config format.

File Matching

This config is meant to be used on top of a base ESLint configuration. It uses the files field to apply itself only to files matched by the following glob patterns:

• **/setupTests.?([cm])[jt]s?(x) → Test setup files.
• **/jest.setup.?([cm])[jt]s?(x) → Test setup files.
• **/test?(s)/**/*.?([cm])[jt]s?(x) → Directories named test / tests.
• **/__@(tests|mocks)__/**/*.?([cm])[jt]s?(x) → Directories named __tests__ / __mocks__.
• **/+(*.)@(spec|test).?([cm])[jt]s?(x) → Files with a .test.* / .spec.* suffix.
• **/test.?([cm])[jt]s?(x) → Files named test.

Note: the pattern .?([cm])[jt]s?(x) matches the file extensions .js, .mjs, .cjs, .jsx, .ts, .mts, .cts, and .tsx.

Additionally, this config uses the ignores field so that it is not applied to any files matched by **/fixtures/** or **/__fixtures__/**.

If you would like to control what files this config is applied to, you can override the files field and use your own glob patterns in your eslint.config.js file:

import jestConfig from '@lcooper/eslint-config-jest';

export default [
    {
        ...jestConfig,
        files: [
            // ... your globs here ...
        ],
    },
];

Related

This package is intended to enhance one of these base configs:

• @lcooper/eslint-config - Base config for standard JavaScript projects
• @lcooper/eslint-config-typescript - Base config for TypeScript projects

See also:

• @lcooper/eslint-config-react - Enhancement config for React projects
• @lcooper/eslint-config-typescript-react - Enhancement config for React projects that use TypeScript
• @lcooper/eslint-plugin - Plugin with awesome extra ESLint rules

License

MIT