Enforce valid titles (valid-title)

Checks that the title of Jest blocks are valid by ensuring that titles are:

• not empty,
• is a string,
• not prefixed with their block name,
• have no leading or trailing spaces

Rule Details

emptyTitle

An empty title is not informative, and serves little purpose.

Examples of incorrect code for this rule:

describe('', () => {});
describe('foo', () => {
  it('', () => {});
});
it('', () => {});
test('', () => {});
xdescribe('', () => {});
xit('', () => {});
xtest('', () => {});

Examples of correct code for this rule:

describe('foo', () => {});
describe('foo', () => {
  it('bar', () => {});
});
test('foo', () => {});
it('foo', () => {});
xdescribe('foo', () => {});
xit('foo', () => {});
xtest('foo', () => {});

titleMustBeString

Titles for test blocks should always be a string.

This is also applied to describe blocks by default, but can be turned off via the ignoreTypeOfDescribeName option:

Examples of incorrect code for this rule:

it(123, () => {});
describe(String(/.+/), () => {});
describe(myFunction, () => {});
xdescribe(myFunction, () => {});
describe(6, function () {});

Examples of correct code for this rule:

it('is a string', () => {});
test('is a string', () => {});
xtest('is a string', () => {});
describe('is a string', () => {});
describe.skip('is a string', () => {});
fdescribe('is a string', () => {});

Examples of correct code when ignoreTypeOfDescribeName is true:

it('is a string', () => {});
test('is a string', () => {});
xtest('is a string', () => {});
describe('is a string', () => {});
describe.skip('is a string', () => {});
fdescribe('is a string', () => {});

describe(String(/.+/), () => {});
describe(myFunction, () => {});
xdescribe(myFunction, () => {});
describe(6, function () {});

duplicatePrefix

A describe / test block should not start with duplicatePrefix

Examples of incorrect code for this rule

test('test foo', () => {});
it('it foo', () => {});

describe('foo', () => {
  test('test bar', () => {});
});

describe('describe foo', () => {
  test('bar', () => {});
});

Examples of correct code for this rule

test('foo', () => {});
it('foo', () => {});

describe('foo', () => {
  test('bar', () => {});
});

accidentalSpace

A describe / test block should not contain accidentalSpace

Examples of incorrect code for this rule

test(' foo', () => {});
it(' foo', () => {});

describe('foo', () => {
  test(' bar', () => {});
});

describe(' foo', () => {
  test('bar', () => {});
});

describe('foo  ', () => {
  test('bar', () => {});
});

Examples of correct code for this rule

test('foo', () => {});
it('foo', () => {});

describe('foo', () => {
  test('bar', () => {});
});

Options

interface Options {
  ignoreTypeOfDescribeName?: boolean;
  disallowedWords?: string[];
  mustNotMatch?: Partial<Record<'describe' | 'test' | 'it', string>> | string;
  mustMatch?: Partial<Record<'describe' | 'test' | 'it', string>> | string;
}

ignoreTypeOfDescribeName

Default: false

When enabled, the type of the first argument to describe blocks won't be checked.

disallowedWords

Default: []

A string array of words that are not allowed to be used in test titles. Matching is not case-sensitive, and looks for complete words:

Examples of incorrect code when using disallowedWords:

// with disallowedWords: ['correct', 'all', 'every', 'properly']
describe('the correct way to do things', () => {});
it('has ALL the things', () => {});
xdescribe('every single one of them', () => {});
test(`that the value is set properly`, () => {});

Examples of correct code when using disallowedWords:

// with disallowedWords: ['correct', 'all', 'every', 'properly']
it('correctly sets the value', () => {});
test('that everything is as it should be', () => {});
describe('the proper way to handle things', () => {});

mustMatch & mustNotMatch

Defaults: {}

Allows enforcing that titles must match or must not match a given Regular Expression, with an optional message. An object can be provided to apply different Regular Expressions (with optional messages) to specific Jest test function groups (describe, test, and it).

Examples of incorrect code when using mustMatch:

// with mustMatch: '^that'
describe('the correct way to do things', () => {});
fit('this there!', () => {});

// with mustMatch: { test: '^that' }
describe('the tests that will be run', () => {});
test('the stuff works', () => {});
xtest('errors that are thrown have messages', () => {});

Examples of correct code when using mustMatch:

// with mustMatch: '^that'
describe('that thing that needs to be done', () => {});
fit('that this there!', () => {});

// with mustMatch: { test: '^that' }
describe('the tests that will be run', () => {});
test('that the stuff works', () => {});
xtest('that errors that thrown have messages', () => {});

Optionally you can provide a custom message to show for a particular matcher by using a tuple at any level where you can provide a matcher:

const prefixes = ['when', 'with', 'without', 'if', 'unless', 'for'];
const prefixesList = prefixes.join('  - \n');

module.exports = {
  rules: {
    'jest/valid-title': [
      'error',
      {
        mustNotMatch: ['\\.$', 'Titles should not end with a full-stop'],
        mustMatch: {
          describe: [
            new RegExp(`^(?:[A-Z]|\\b(${prefixes.join('|')})\\b`, 'u').source,
            `Describe titles should either start with a capital letter or one of the following prefixes: ${prefixesList}`,
          ],
          test: [/[^A-Z]/u.source],
          it: /[^A-Z]/u.source,
        },
      },
    ],
  },
};