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eslint-plugin-jest

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eslint-plugin-jest

ESLint rules for Jest

    27.1.6latest

Version published
Maintainers
11
Weekly downloads
7,783,639
decreased by-14.35%

Weekly downloads

Changelog

Source

27.1.6 (2022-11-24)

Bug Fixes

  • ensure rule fixes produce valid code when function params and args have trailing commas (#1282) (8eca0b7)

Readme

Source

eslint-plugin-jest

ESLint plugin for Jest

Actions Status

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 tell ESLint about the environment variables provided by Jest by doing:

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

This is included in all configs shared by this plugin, so can be omitted if extending them.

Aliased Jest globals

You can tell this plugin about any global Jests you have aliased using the globalAliases setting:

{ "settings": { "jest": { "globalAliases": { "describe": ["context"], "fdescribe": ["fcontext"], "xdescribe": ["xcontext"] } } } }

The rules provided by this plugin assume that the files they are checking are test-related. This means it's generally not suitable to include them in your top-level configuration as that applies to all files being linted which can include source files.

You can use overrides to have ESLint apply additional rules to specific files:

{ "extends": ["eslint:recommended"], "overrides": [ { "files": ["test/**"], "plugins": ["jest"], "extends": ["plugin:jest/recommended"], "rules": { "jest/prefer-expect-assertions": "off" } } ], "rules": { "indent": ["error", 2] } }

Jest version setting

The behaviour of some rules (specifically no-deprecated-functions) change depending on the version of Jest being used.

By default, this plugin will attempt to determine to locate Jest using require.resolve, meaning it will start looking in the closest node_modules folder to the file being linted and work its way up.

Since we cache the automatically determined version, if you're linting sub-folders that have different versions of Jest, you may find that the wrong version of Jest is considered when linting. You can work around this by providing the Jest version explicitly in nested ESLint configs:

{ "settings": { "jest": { "version": 27 } } }

To avoid hard-coding a number, you can also fetch it from the installed version of Jest if you use a JavaScript config file such as .eslintrc.js:

module.exports = { settings: { jest: { version: require('jest/package.json').version, }, }, };

Shareable configurations

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).

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

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

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

💼 Configurations enabled in.
⚠️ Configurations set to warn in.
✅ Set in the recommended configuration.
🎨 Set in the style configuration.
🔧 Automatically fixable by the --fix CLI option.
💡 Manually fixable by editor suggestions.
❌ Deprecated.

Name                         Description💼⚠️🔧💡❌
consistent-test-itEnforce test and it usage conventions🔧
expect-expectEnforce assertion to be made in a test body✅
max-expectsEnforces a maximum number assertion calls in a test body
max-nested-describeEnforces a maximum depth to nested describe calls
no-alias-methodsDisallow alias methods✅🎨🔧
no-commented-out-testsDisallow commented out tests✅
no-conditional-expectDisallow calling expect conditionally✅
no-conditional-in-testDisallow conditional logic in tests
no-deprecated-functionsDisallow use of deprecated functions✅🔧
no-disabled-testsDisallow disabled tests✅
no-done-callbackDisallow using a callback in asynchronous tests and hooks✅💡
no-duplicate-hooksDisallow duplicate setup and teardown hooks
no-exportDisallow using exports in files containing tests✅
no-focused-testsDisallow focused tests✅💡
no-hooksDisallow setup and teardown hooks
no-identical-titleDisallow identical titles✅
no-ifDisallow conditional logic❌
no-interpolation-in-snapshotsDisallow string interpolation inside snapshots✅
no-jasmine-globalsDisallow Jasmine globals✅🔧
no-large-snapshotsDisallow large snapshots
no-mocks-importDisallow manually importing from __mocks__✅
no-restricted-jest-methodsDisallow specific jest. methods
no-restricted-matchersDisallow specific matchers & modifiers
no-standalone-expectDisallow using expect outside of it or test blocks✅
no-test-prefixesRequire using .only and .skip over f and x✅🔧
no-test-return-statementDisallow explicitly returning from tests
prefer-called-withSuggest using toBeCalledWith() or toHaveBeenCalledWith()
prefer-comparison-matcherSuggest using the built-in comparison matchers🔧
prefer-eachPrefer using .each rather than manual loops
prefer-equality-matcherSuggest using the built-in equality matchers💡
prefer-expect-assertionsSuggest using expect.assertions() OR expect.hasAssertions()💡
prefer-expect-resolvesPrefer await expect(...).resolves over expect(await ...) syntax🔧
prefer-hooks-in-orderPrefer having hooks in a consistent order
prefer-hooks-on-topSuggest having hooks before any test cases
prefer-lowercase-titleEnforce lowercase test names🔧
prefer-mock-promise-shorthandPrefer mock resolved/rejected shorthands for promises🔧
prefer-snapshot-hintPrefer including a hint with external snapshots
prefer-spy-onSuggest using jest.spyOn()🔧
prefer-strict-equalSuggest using toStrictEqual()💡
prefer-to-beSuggest using toBe() for primitive literals🎨🔧
prefer-to-containSuggest using toContain()🎨🔧
prefer-to-have-lengthSuggest using toHaveLength()🎨🔧
prefer-todoSuggest using test.todo🔧
require-hookRequire setup and teardown code to be within a hook
require-to-throw-messageRequire a message for toThrow()
require-top-level-describeRequire test cases and hooks to be inside a describe block
valid-describe-callbackEnforce valid describe() callback✅
valid-expectEnforce valid expect() usage✅
valid-expect-in-promiseRequire promises that have expectations in their chain to be valid✅
valid-titleEnforce valid titles✅🔧

Requires Type Checking

Name          Description💼⚠️🔧💡❌
unbound-methodEnforce unbound methods are called with their expected scope

In order to use the rules powered by TypeScript type-checking, you must be using @typescript-eslint/parser & adjust your eslint config as outlined here.

Note that unlike the type-checking rules in @typescript-eslint/eslint-plugin, the rules here will fallback to doing nothing if type information is not available, meaning it's safe to include them in shared configs that could be used on JavaScript and TypeScript projects.

Also note that unbound-method depends on @typescript-eslint/eslint-plugin, as it extends the original unbound-method rule from that plugin.

Credit

eslint-plugin-jest-extended

This is a sister plugin to eslint-plugin-jest that provides support for the matchers provided by jest-extended.

https://github.com/jest-community/eslint-plugin-jest-extended

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

eslint-plugin-istanbul

A set of rules to enforce good practices for Istanbul, one of the code coverage tools used by Jest.

https://github.com/istanbuljs/eslint-plugin-istanbul

Keywords

FAQs

What is eslint-plugin-jest?

ESLint rules for Jest

Is eslint-plugin-jest popular?

The npm package eslint-plugin-jest receives a total of 6,253,728 weekly downloads. As such, eslint-plugin-jest popularity was classified as popular.

Is eslint-plugin-jest well maintained?

We found that eslint-plugin-jest demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago.It has 11 open source maintainers collaborating on the project.

Last updated on 24 Nov 2022

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