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.
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 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"]
}
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 | Enforce consistent test or it keyword |  | |
| expect-expect | Enforce assertion to be made in a test body | ||
| lowercase-name | Disallow capitalized test names | | |
| no-alias-methods | Disallow alias methods |  | |
| no-commented-out-tests | Disallow commented out tests | ||
| no-disabled-tests | Disallow disabled tests | | |
| no-duplicate-hooks | Disallow duplicate hooks within a describe block | ||
| no-empty-title | Disallow empty titles | ||
| no-expect-resolves | Disallow using expect().resolves | ||
| no-export | Disallow export from test files | ||
| 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-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-standalone-expect | Prevents expect statements outside of a test or it block | ||
| no-test-callback | Using a callback in asynchronous tests | | |
| no-test-prefixes | Disallow using f & x prefixes to define focused/skipped tests | | |
| no-test-return-statement | Disallow explicitly returning from tests | ||
| no-truthy-falsy | Disallow using toBeTruthy() & toBeFalsy() | ||
| no-try-expect | Prevent catch assertions in tests | ||
| prefer-called-with | Suggest using toBeCalledWith() OR toHaveBeenCalledWith() | ||
| prefer-expect-assertions | Suggest using expect.assertions() OR expect.hasAssertions() | ||
| prefer-hooks-on-top | Suggest to have all hooks at top-level before tests | ||
| prefer-inline-snapshots | Suggest using toMatchInlineSnapshot() | | |
| 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-top-level-describe | Require a top-level describe block | ||
| require-tothrow-message | Require that toThrow() and toThrowError includes a message | ||
| valid-describe | Enforce valid describe() callback | | |
| valid-expect-in-promise | Enforce having return statement when testing with promises | | |
| valid-expect | Enforce valid expect() usage | | |
| valid-title | Enforce valid titles for jest blocks |
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 8,815,016 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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