eslint-plugin-jest

ESLint plugin for Jest

Installation

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

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

Usage

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

{
  "plugins": ["jest"]
}

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

{
  "rules": {
    "jest/no-disabled-tests": "warn",
    "jest/no-focused-tests": "error",
    "jest/no-identical-title": "error",
    "jest/prefer-to-have-length": "warn",
    "jest/valid-expect": "error"
  }
}

You can also whitelist the environment variables provided by Jest by doing:

{
  "env": {
    "jest/globals": true
  }
}

Shareable configurations

Recommended

This plugin exports a recommended configuration that enforces good testing practices.

To enable this configuration use the extends property in your .eslintrc config file:

{
  "extends": ["plugin:jest/recommended"]
}

See ESLint documentation for more information about extending configuration files.

Rules

Rule	Description	Recommended	Fixable
no-disabled-tests	Disallow disabled tests
no-focused-tests	Disallow focused tests
no-identical-title	Disallow identical titles
no-large-snapshots	Disallow large snapshots
prefer-to-have-length	Suggest using toHaveLength()
prefer-to-be-null	Suggest using toBeNull()
prefer-to-be-undefined	Suggest using toBeUndefined()
prefer-expect-assertions	Suggest using expect.assertions() OR expect.hasAssertions()
valid-expect	Enforce valid expect() usage
valid-expect-in-promise	Enforce having return statement when testing with promises

Credit

• eslint-plugin-mocha
• eslint-plugin-jasmine