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eslint-plugin-jest
Advanced tools
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.
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/valid-expect": "error"
}
}
You can also whitelist the environment variables provided by Jest by doing:
{
"env": {
"jest/globals": true
}
}
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.
The rules enabled in this configuration are:
FAQs
ESLint rules for Jest
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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