#valid-mock-module-path

#Configuration

import { defineConfig, jestPlugin } from '@rslint/core';

export default defineConfig([
  jestPlugin.configs.recommended,
  {
    rules: {
      'jest/valid-mock-module-path': 'error',
    },
  },
]);

#Rule Details

Disallow mocking of non-existing module paths.

This rule reports jest.mock() and jest.doMock() calls whose first argument names a module that cannot be found. Only a string literal is checked; a variable, template literal or other expression is ignored.

A path starting with . is resolved against the directory of the linted file. It exists when a file or directory is found at that path, or at that path followed by one of the moduleFileExtensions. Any other specifier is resolved the way Node's require.resolve resolves it: Node built-in modules are always accepted, packages are looked up in node_modules directories, and a package's exports field is honored with the require condition, so a path the package does not export is reported even when the file exists.

A call passing a third argument that is an object literal with a virtual property set to a truthy literal, such as { virtual: true }, is not checked, because Jest does not require a virtual module to exist.

Examples of incorrect code for this rule:

// Module(s) that cannot be found
jest.mock('@org/some-module-not-in-package-json');
jest.mock('some-module-not-in-package-json');

// Local module (directory) that cannot be found
jest.mock('../../this/module/does/not/exist');

// Local file that cannot be found
jest.mock('../../this/path/does/not/exist.js');

// Local file that cannot be found and is NOT virtual
jest.mock('../../this/path/does/not/exist.js', undefined, { virtual: false });

Examples of correct code for this rule:

// Module(s) that can be found
jest.mock('@org/some-module-in-package-json');
jest.mock('some-module-in-package-json');

// Local module that can be found
jest.mock('../../this/module/really/does/exist');

// Local file that can be found
jest.mock('../../this/path/really/does/exist.js');

// Module(s) that cannot be found but are configured as virtual
jest.mock('@org/some-module-not-in-package-json', undefined, { virtual: true });
jest.mock('some-module-not-in-package-json', undefined, { virtual: true });

// Local file that cannot be found but is configured as virtual
jest.mock('../../this/path/does/not/exist.js', undefined, { virtual: true });

#Options

{
  "jest/valid-mock-module-path": [
    "error",
    {
      "moduleFileExtensions": [".js", ".ts", ".jsx", ".tsx", ".json"]
    }
  ]
}

#moduleFileExtensions

The file extensions tried after a local path that does not exist as written. The default extensions are:

• ".js"
• ".ts"
• ".jsx"
• ".tsx"
• ".json"

Each extension is appended to the path as written, so a custom extension must include its leading dot. This option does not affect package specifiers.

#Differences from ESLint

• Package specifiers are looked up in node_modules directories starting from the linted file's directory, the way Jest looks them up when running the test. eslint-plugin-jest looks them up from its own install location instead. The results differ only when a package is installed where one location can see it and the other cannot, for example in a nested package of a monorepo.
• For the same reason, a # subpath import such as jest.mock('#utils') is resolved through the imports field of the package.json that owns the linted file, and is accepted when that field maps it to an existing file. eslint-plugin-jest reports every # import.

#When Not To Use It

Don't use this rule on non-jest test files.

#Original Documentation

• eslint-plugin-jest: valid-mock-module-path
• Source code