jest-webpack-alias

3.3.4 verified Sat Apr 25 auth: no javascript deprecated

Jest preprocessor that resolves require() statements using webpack aliases. Version 3.3.4 (latest, no stable release cadence). Allows Jest to understand webpack alias resolution, but is deprecated in favor of babel-plugin-module-resolver. Handles JavaScript and non-JavaScript files through mocks, but AST limitations prevent dynamic require() resolution. Works with webpack multi-compiler profiles. Limited to webpack 1/2/3 style configurations.

Common errors

error Cannot find module 'some-module' ↓

cause Webpack alias not resolved by Jest without this preprocessor.

fix

Set up jest-webpack-alias preprocessor as described in the README.

error TypeError: webpackAlias.process is not a function ↓

cause Incorrect import: using ESM import syntax on a CommonJS module.

fix

Use require('jest-webpack-alias') instead of import.

Warnings

deprecated Package is deprecated; consider using babel-plugin-module-resolver instead. ↓

fix Replace with babel-plugin-module-resolver and configure Jest moduleNameMapper for aliases.

gotcha Dynamic require() with variables is not supported by the AST parser. ↓

fix Use resolve() function: require(resolve(moduleName, __filename))

gotcha Non-JavaScript file requires (e.g., CSS) are not resolved; require('./style.css') fails. ↓

fix Manual mock the file in __mocks__ directory, or use ignore-styles.

gotcha resolve.modulesDirectories only searches the package.json directory, not ancestors. ↓

fix Ensure modulesDirectories is relative to package.json location.

Install

npm install jest-webpack-alias

yarn add jest-webpack-alias

pnpm add jest-webpack-alias

Imports

jest-webpack-alias
wrong
```
import webpackAlias from 'jest-webpack-alias'
```
correct
```
require('jest-webpack-alias')
```
CommonJS module; only works with require, not ESM default import.

resolve

wrong

const resolve = require('jest-webpack-alias').resolve

correct

const { resolve } = require('jest-webpack-alias')

Exported member for manual resolution of dynamic requires.

Quickstart

Shows the typical setup for a Jest preprocessor that applies babel-jest and webpack alias resolution.

// __tests__/preprocessor.js
var babelJest = require('babel-jest');
require('babel-register');
var webpackAlias = require('jest-webpack-alias');

module.exports = {
  process: function(src, filename) {
    if (filename.indexOf('node_modules') === -1) {
      src = babelJest.process(src, filename);
      src = webpackAlias.process(src, filename);
    }
    return src;
  }
};