eslint-plugin-jestx

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"]
}

Style

This plugin also exports a configuration named style, which adds some stylistic rules, such as prefer-to-be-null, which enforces usage of toBeNull over toBe(null). All rules included are:

• prefer-to-be-null
• prefer-to-be-undefined
• prefer-to-contain
• prefer-to-have-length

See ESLint documentation for more information about extending configuration files.

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:

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

While the recommended and style configurations only change in major versions the all configuration may change in any release and is thus unsuited for installations requiring long-term consistency.

Rules

Rule	Description	Recommended	Fixable
consistent-test-it	Enforce consistent test or it keyword
expect-expect	Enforce assertion to be made in a test body
lowercase-name	Disallow capitalized test names
no-alias-methods	Disallow alias methods
no-disabled-tests	Disallow disabled tests
no-commented-out-tests	Disallow commented out tests
no-empty-title	Disallow empty titles
no-focused-tests	Disallow focused tests
no-hooks	Disallow setup and teardown hooks
no-identical-title	Disallow identical titles
no-jasmine-globals	Disallow Jasmine globals
no-jest-import	Disallow importing jest
no-mocks-import	Disallow manually importing from __mocks__
no-large-snapshots	Disallow large snapshots
no-test-callback	Using a callback in asynchronous tests
no-test-prefixes	Disallow using f & x prefixes to define focused/skipped tests
no-test-return-statement	Disallow explicitly returning from tests
no-truthy-falsy	Disallow using toBeTruthy() & toBeFalsy()
prefer-expect-assertions	Suggest using expect.assertions() OR expect.hasAssertions()
prefer-spy-on	Suggest using jest.spyOn()
prefer-strict-equal	Suggest using toStrictEqual()
prefer-to-be-null	Suggest using toBeNull()
prefer-to-be-undefined	Suggest using toBeUndefined()
prefer-to-contain	Suggest using toContain()
prefer-to-have-length	Suggest using toHaveLength()
prefer-inline-snapshots	Suggest using toMatchInlineSnapshot()
require-tothrow-message	Require that toThrow() and toThrowError includes a message
valid-describe	Enforce valid describe() callback
valid-expect-in-promise	Enforce having return statement when testing with promises
valid-expect	Enforce valid expect() usage
prefer-todo	Suggest using test.todo()
prefer-called-with	Suggest using toBeCalledWith() OR toHaveBeenCalledWith()

Credit

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

Related Projects

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