prefer-lowercase-title.md

Enforce lowercase test names (prefer-lowercase-title)

🔧 This rule is automatically fixable by the --fix CLI option.

Rule details

Enforce it, test and describe to have descriptions that begin with a lowercase letter. This provides more readable test failures. This rule is not enabled by default.

The following pattern is considered a warning:

it('Adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});

The following pattern is not considered a warning:

it('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});

Options

{
  "jest/prefer-lowercase-title": [
    "error",
    {
      "ignore": ["describe", "test"]
    }
  ]
}

ignore

This array option controls which Jest functions are checked by this rule. There are three possible values:

• "describe"
• "test"
• "it"

By default, none of these options are enabled (the equivalent of { "ignore": [] }).

Example of correct code for the { "ignore": ["describe"] } option:

/* eslint jest/prefer-lowercase-title: ["error", { "ignore": ["describe"] }] */

describe('Uppercase description');

Example of correct code for the { "ignore": ["test"] } option:

/* eslint jest/prefer-lowercase-title: ["error", { "ignore": ["test"] }] */

test('Uppercase description');

Example of correct code for the { "ignore": ["it"] } option:

/* eslint jest/prefer-lowercase-title: ["error", { "ignore": ["it"] }] */

it('Uppercase description');

allowedPrefixes

This array option allows specifying prefixes, which contain capitals that titles can start with. This can be useful when writing tests for API endpoints, where you'd like to prefix with the HTTP method.

By default, nothing is allowed (the equivalent of { "allowedPrefixes": [] }).

Example of correct code for the { "allowedPrefixes": ["GET"] } option:

/* eslint jest/prefer-lowercase-title: ["error", { "allowedPrefixes": ["GET"] }] */

describe('GET /live');

ignoreTopLevelDescribe

This option can be set to allow only the top-level describe blocks to have a title starting with an upper-case letter.

Example of correct code for the { "ignoreTopLevelDescribe": true } option:

/* eslint jest/prefer-lowercase-title: ["error", { "ignoreTopLevelDescribe": true }] */
describe('MyClass', () => {
  describe('#myMethod', () => {
    it('does things', () => {
      //
    });
  });
});