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

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.

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

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