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    eslint-plugin-jest

    25.2.2 • Public • Published

    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.

    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

    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).

    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

    Rule Description Configurations Fixable
    consistent-test-it Have control over test and it usages fixable
    expect-expect Enforce assertion to be made in a test body recommended
    max-nested-describe Enforces a maximum depth to nested describe calls
    no-alias-methods Disallow alias methods style fixable
    no-commented-out-tests Disallow commented out tests recommended
    no-conditional-expect Prevent calling expect conditionally recommended
    no-deprecated-functions Disallow use of deprecated functions recommended fixable
    no-disabled-tests Disallow disabled tests recommended
    no-done-callback Avoid using a callback in asynchronous tests and hooks recommended suggest
    no-duplicate-hooks Disallow duplicate setup and teardown hooks
    no-export Disallow using exports in files containing tests recommended
    no-focused-tests Disallow focused tests recommended suggest
    no-hooks Disallow setup and teardown hooks
    no-identical-title Disallow identical titles recommended
    no-if Disallow conditional logic
    no-interpolation-in-snapshots Disallow string interpolation inside snapshots recommended
    no-jasmine-globals Disallow Jasmine globals recommended fixable
    no-jest-import Disallow importing Jest recommended
    no-large-snapshots disallow large snapshots
    no-mocks-import Disallow manually importing from __mocks__ recommended
    no-restricted-matchers Disallow specific matchers & modifiers
    no-standalone-expect Disallow using expect outside of it or test blocks recommended
    no-test-prefixes Use .only and .skip over f and x recommended fixable
    no-test-return-statement Disallow explicitly returning from tests
    prefer-called-with Suggest using toBeCalledWith() or toHaveBeenCalledWith()
    prefer-expect-assertions Suggest using expect.assertions() OR expect.hasAssertions() suggest
    prefer-expect-resolves Prefer await expect(...).resolves over expect(await ...) syntax fixable
    prefer-hooks-on-top Suggest having hooks before any test cases
    prefer-lowercase-title Enforce lowercase test names fixable
    prefer-spy-on Suggest using jest.spyOn() fixable
    prefer-strict-equal Suggest using toStrictEqual() suggest
    prefer-to-be Suggest using toBe() for primitive literals style fixable
    prefer-to-contain Suggest using toContain() style fixable
    prefer-to-have-length Suggest using toHaveLength() style fixable
    prefer-todo Suggest using test.todo fixable
    require-hook Require setup and teardown code to be within a hook
    require-to-throw-message Require a message for toThrow()
    require-top-level-describe Require test cases and hooks to be inside a describe block
    valid-describe-callback Enforce valid describe() callback recommended
    valid-expect Enforce valid expect() usage recommended
    valid-expect-in-promise Ensure promises that have expectations in their chain are valid recommended
    valid-title Enforce valid titles recommended fixable

    TypeScript Rules

    In addition to the above rules, this plugin also includes a few advanced rules that are powered by type-checking information provided by TypeScript.

    In order to use these rules, 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 its 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.

    Rule Description Configurations Fixable
    unbound-method Enforces unbound methods are called with their expected scope

    Credit

    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

    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

    Install

    npm i eslint-plugin-jest@25.2.2

    Version

    25.2.2

    License

    MIT

    Unpacked Size

    294 kB

    Total Files

    95

    Last publish

    Collaborators

    • simenb
    • rickhanlonii
    • thymikee
    • jsonp
    • orta
    • rogeliog
    • mattphillips
    • jeysal
    • rubennorte
    • fb
    • aaronabramov