jest-mock-without-import.md

jest-mock-without-import

Reasons to install this ESLint rule

• The path in jest.mock(...) has no autocompletion (like import/require has)
• The path is not covered by refactoring rules of IDEs when moving or renaming files
• The path is not covered by the jest ESLint rules
• The path is not covered by other famous ESLint rules like import/no-unresolved
• The path is not covered by tsc when using TypeScript

=> only running the tests could reveal the error

Correct usages

using import

code:

import someFunction from 'some-package';

jest.mock('some-package');

code:

import someFunction from '../some/path/to/file';

jest.mock('../some/path/to/file');

using import with destructoring

code:

import { someFunction } from 'some-package';

jest.mock('some-package');

code:

import { someFunction } from '../some/path/to/file';

jest.mock('../some/path/to/file');

using import with "*" syntax

code:

import * as someFunction from 'some-package';

jest.mock('some-package');

code:

import * as someFunction from '../some/path/to/file';

jest.mock('../some/path/to/file');

using require

code:

const someFunction = require('some-package');

jest.mock('some-package');

code:

const someFunction = require('../some/path/to/file');

jest.mock('../some/path/to/file');

using require with destructoring

code:

const { someFunction } = require('some-package');

jest.mock('some-package');

code:

const { someFunction } = require('../some/path/to/file');

jest.mock('../some/path/to/file');

with configuration ignorePaths

code:

jest.mock('some-package');

configuration:

['error', { ignorePaths: ['some-package'] }]

with configuration ignorePatterns using a string

code:

jest.mock('some-package');

configuration:

['error', { ignorePatterns: ['some-.*'] }]

with configuration ignorePatterns using a regex

code:

jest.mock('some-package');

configuration:

['error', { ignorePatterns: [/some-.*/ }]

with configuration ignoreMockWithFactory

code:

jest.mock('some-package', () => { someFunction: jest.mock() });

configuration:

['error', { ignoreMockWithFactory: true }]

with configuration ignoreVirtual

code:

jest.mock('some-package', () => { someFunction: jest.mock() }, { virtual: true });

configuration:

['error', { ignoreVirtual: true }]

Incorrect usages

absolute path without import

code:

jest.mock('some-package');

relative path without import

code:

jest.mock('../path/to/someFile');

absolute path with factory without import

code:

jest.mock('some-package', () => { someFunction: jest.fn() });

Configuration

There are multiple ways to exclude jest.mock calls.

This might be useful / necessary when:

• using a factory for mocking without the need to override it
• using an external mock file like __mocks__/<file-to-mock> without the need to override it

Configuration	Type	Consequence
ignorePaths	string[]	Paths added to this array are ignored. So no linting error is thrown, even if this path is not imported into the test file but used in jest.mock
ignorePatterns	string[] / Regex Array	Basically the same as ignorePaths, but Regular Expressions (as string or Regex) can be used.
ignoreMockWithFactory	boolean	The second parameter of the jest.mock() function is a so called factory. It allows to directly specify the mock without using .mockReturnValue. If ignoreMockWithFactory is set to true, jest.mock() calls with a factory set, are not checked.
ignoreVirtual	boolean	The third parameter of jest.mock() allows to pass options. virtual allows mocking of modules, which don't exist in the system. This might be useful for native modules (like e.g. react-native has).

Example

'jest-mock-path/detect-jest-mock-without-import': ['error', {
  ignorePaths: ['some-path'],
  ignorePatterns: ['pattern-as-string', /pattern-as-regex/],
  ignoreMockWithFactory: true
}],