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eslint-plugin-jest

ESLint plugin for Jest

yarn add --dev eslint eslint-plugin-jest

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

If you're using flat configuration:

Withflat configuration,just import the plugin and away you go:

constpluginJest=require('eslint-plugin-jest');module.exports=[{// update this to match your test filesfiles:['**/*.spec.js','**/*.test.js'],plugins:{jest:pluginJest},languageOptions:{globals:pluginJest.environments.globals.globals,},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',},},];

With legacy configuration, addjest to the plugins section of your.eslintrcconfiguration file. You can omit theeslint-plugin- prefix:

{"plugins": ["jest"],"env": {"jest/globals":true  },"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 tell this plugin about any global Jests you have aliased using theglobalAliases setting:

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

You can tell this plugin to treat a different package as the source of Jestglobals using theglobalPackage setting:

{"settings": {"jest": {"globalPackage":"bun:test"    }  }}

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

For.eslintrc configs you can useoverridesto 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]  }}

Foreslint.config.js you can usefiles andignores:

constjest=require('eslint-plugin-jest');module.exports=[  ...require('@eslint/js').configs.recommended,{files:['test/**'],    ...jest.configs['flat/recommended'],rules:{      ...jest.configs['flat/recommended'].rules,'jest/prefer-expect-assertions':'off',},},// you can also configure jest rules in other objects, so long as some of the `files` match{files:['test/**'],rules:{'jest/prefer-expect-assertions':'off'},},];

The behaviour of some rules (specificallyno-deprecated-functions) changedepending on the version of Jest being used.

By default, this plugin will attempt to determine to locate Jest usingrequire.resolve, meaning it will start looking in the closestnode_modulesfolder to the file being linted and work its way up.

Since we cache the automatically determined version, if you're lintingsub-folders that have different versions of Jest, you may find that the wrongversion of Jest is considered when linting. You can work around this byproviding 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 versionof Jest if you use a JavaScript config file such as.eslintrc.js:

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

This plugin exports a recommended configuration that enforces good testingpractices.

To enable this configuration with.eslintrc, use theextends property:

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

To enable this configuration witheslint.config.js, usejest.configs['flat/recommended']:

constjest=require('eslint-plugin-jest');module.exports=[{files:[/* glob matching your test files */],    ...jest.configs['flat/recommended'],},];

This plugin also exports a configuration namedstyle, which adds somestylistic rules, such asprefer-to-be-null, which enforces usage oftoBeNullovertoBe(null).

To enable this configuration use theextends property in your.eslintrcconfig file:

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

To enable this configuration witheslint.config.js, usejest.configs['flat/style']:

constjest=require('eslint-plugin-jest');module.exports=[{files:[/* glob matching your test files */],    ...jest.configs['flat/style'],},];

If you want to enable all rules instead of only some you can do so by adding theall configuration to your.eslintrc config file:

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

To enable this configuration witheslint.config.js, usejest.configs['flat/all']:

constjest=require('eslint-plugin-jest');module.exports=[{files:[/* glob matching your test files */],    ...jest.configs['flat/all'],},];

While therecommended andstyle configurations only change in major versionstheall configuration may change in any release and is thus unsuited forinstallations requiring long-term consistency.

💼Configurationsenabled in.
⚠️Configurationsset to warn in.
✅ Set in therecommendedconfiguration.
🎨Set in thestyleconfiguration.
🔧Automatically fixable by the--fix CLI option.
💡Manually fixable byeditor suggestions.

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

Note that unlike the type-checking rules in@typescript-eslint/eslint-plugin,the rules here will fallback to doing nothing if type information is notavailable, meaning it's safe to include them in shared configs that could beused on JavaScript and TypeScript projects.

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

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

This is a sister plugin toeslint-plugin-jest that provides support for thematchers provided byjest-extended.

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

This project aims to provide formatting rules (auto-fixable where possible) toensure consistency and readability in jest test suites.

https://github.com/dangreenisrael/eslint-plugin-jest-formatting

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

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