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eslint-plugin-jest

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

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