eslint-plugin-jest
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Package description
The eslint-plugin-jest package is an ESLint plugin that provides linting rules for Jest, a popular JavaScript testing framework. It helps maintain code quality and enforce best practices by analyzing test files for common issues and stylistic preferences.
Enforcing consistent test descriptions
This rule enforces a consistent test function name, either `test` or `it`, within the test files.
/* eslint jest/consistent-test-it: ["error", { fn: "test" }] */
// Incorrect
describe('myFeature', () => {
it('does something', () => {
// test implementation
});
});
// Correct
describe('myFeature', () => {
test('does something', () => {
// test implementation
});
});Preventing disabled tests
This rule prevents the use of `xdescribe`, `xit`, or `test.skip`, which are used to disable tests, to ensure that all tests are run.
/* eslint jest/no-disabled-tests: "error" */
// Incorrect
xdescribe('myFeature', () => {
test('does something', () => {});
});
xit('does something', () => {});
// Correct
describe('myFeature', () => {
test('does something', () => {});
});Ensuring tests contain assertions
This rule ensures that test blocks contain at least one assertion call, which is necessary for a meaningful test.
/* eslint jest/expect-expect: "error" */
// Incorrect
test('does something', () => {
// no assertions
});
// Correct
test('does something', () => {
expect(something).toBe(true);
});Disallowing identical titles
This rule disallows using the same title for multiple test cases or `describe` blocks, which can cause confusion when trying to identify tests.
/* eslint jest/no-identical-title: "error" */
// Incorrect
describe('myFeature', () => {
test('does something', () => {});
test('does something', () => {});
});
// Correct
describe('myFeature', () => {
test('does something', () => {});
test('does something else', () => {});
});This package provides linting rules for Mocha, another JavaScript test framework. It is similar to eslint-plugin-jest but tailored for Mocha's API and conventions.
This package offers linting rules for Jasmine, a behavior-driven development framework for testing JavaScript code. It serves a similar purpose to eslint-plugin-jest but is specific to Jasmine's syntax and style.
This ESLint plugin enforces best practices for the Testing Library, which is often used with Jest for testing React components. It complements eslint-plugin-jest by focusing on the specific patterns and practices of the Testing Library.
This plugin provides linting rules for Cypress, an end-to-end testing framework. While it is not specific to Jest, it offers similar functionality for maintaining code quality in a different testing context.
Changelog
Readme
ESLint plugin for Jest
$ yarn add --dev eslint eslint-plugin-jest
Note: If you installed ESLint globally then you must also install
eslint-plugin-jest globally.
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
}
}
The behaviour of some rules (specifically no-deprecated-functions) change
depending on the version of jest being used.
This setting is detected automatically based off the version of the jest
package installed in node_modules, but it can also be provided explicitly if
desired:
{
"settings": {
"jest": {
"version": 26
}
}
}
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"]
}
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.
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.
| Rule | Description | Configurations | Fixable |
|---|---|---|---|
| consistent-test-it | Have control over test and it usages |  | |
| expect-expect | Enforce assertion to be made in a test body |  | |
| lowercase-name | Enforce lowercase test names | | |
| no-alias-methods | Disallow alias methods |  | |
| no-commented-out-tests | Disallow commented out tests | | |
| no-conditional-expect | Prevent calling expect conditionally | ||
| no-deprecated-functions | Disallow use of deprecated functions | | |
| no-disabled-tests | Disallow disabled tests | | |
| no-duplicate-hooks | Disallow duplicate setup and teardown hooks | ||
| no-export | Disallow using exports in files containing tests | | |
| no-focused-tests | Disallow focused tests | | |
| no-hooks | Disallow setup and teardown hooks | ||
| no-identical-title | Disallow identical titles | | |
| no-if | Disallow conditional logic | ||
| no-interpolation-in-snapshots | Disallow string interpolation inside snapshots | ||
| no-jasmine-globals | Disallow Jasmine globals | | |
| no-jest-import | Disallow importing Jest | | |
| no-large-snapshots | disallow large snapshots | ||
| no-mocks-import | Disallow manually importing from __mocks__ | | |
| no-restricted-matchers | Disallow specific matchers & modifiers | ||
| no-standalone-expect | Disallow using expect outside of it or test blocks | | |
| no-test-callback | Avoid using a callback in asynchronous tests | |  |
| no-test-prefixes | Use .only and .skip over f and x | | |
| 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() | | |
| prefer-hooks-on-top | Suggest having hooks before any test cases | ||
| 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-todo | Suggest using test.todo | | |
| 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 | Enforce valid describe() callback | | |
| valid-expect | Enforce valid expect() usage | | |
| valid-expect-in-promise | Enforce having return statement when testing with promises | | |
| valid-title | Enforce valid titles | |
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
FAQs
ESLint rules for Jest
The npm package eslint-plugin-jest receives a total of 8,608,187 weekly downloads. As such, eslint-plugin-jest popularity was classified as popular.
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 9 open source maintainers collaborating on the project.
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