rewire-webpack

1.0.1 verified Sat Apr 25 auth: no javascript maintenance

A webpack plugin that enables rewire.js dependency injection for client-side bundles generated by webpack. Currently at version 1.0.1, stable. It allows you to mock and inspect modules within webpack bundles for unit testing. Differentiator: integrates rewire's `__set__`, `__get__`, and `__with__` methods into the browser context, which is not natively possible. Works with webpack 1.x; no recent updates since 2015.

Common errors

error Cannot find module 'rewire-webpack' ↓

cause Package not installed or incorrectly required in webpack config.

fix

Run npm install rewire-webpack --save-dev and use var RewirePlugin = require('rewire-webpack');

error TypeError: myModule.__set__ is not a function ↓

cause RewirePlugin not added to webpack plugins, or module not wired correctly.

fix

Add new RewirePlugin() to webpack's plugins array, and ensure you are using require('rewire') before calling rewire('./module').

error Uncaught ReferenceError: __webpack_require__ is not defined ↓

cause Using rewire in a non-webpack environment (e.g., Node.js without bundling).

fix

Rewire-webpack is for browser bundles; use plain require('rewire') in Node.js tests.

Warnings

gotcha RewirePlugin only works with webpack 1.x; not compatible with webpack 2+ (breaking changes in plugin API). ↓

fix Use an alternative like babel-plugin-rewire or upgrade to webpack 2 with a shim.

gotcha Do not use `__set__({ key: value })`; it must be two separate arguments. ↓

fix Use `__set__('key', value)` instead of an object.

gotcha Cannot rewire modules that use ES module syntax (import/export) without additional Babel transforms. ↓

fix Use rewire's Babel plugin or transpile to CommonJS before bundling.

deprecated Package is unmaintained; last release in 2015. ↓

fix Consider using rewiremock or babel-plugin-rewire for modern projects.

gotcha The plugin may cause issues with webpack's hot module replacement (HMR). ↓

fix Disable HMR when using RewirePlugin, or only use for test builds.

Install

npm install rewire-webpack

yarn add rewire-webpack

pnpm add rewire-webpack

Imports

RewirePlugin

wrong

import RewirePlugin from 'rewire-webpack';

correct

const RewirePlugin = require('rewire-webpack');

Package is CommonJS only; ESM import not available.

rewire
wrong
```
import rewire from 'rewire';
```
correct
```
const rewire = require('rewire');
```
rewire package itself is also CommonJS; must be required.

__set__

wrong

myModule.__set__({ variable: value });

correct

const myModule = rewire('./myModule'); myModule.__set__('variable', value);

__set__ expects two arguments (key, value), not an object.

__get__

wrong

const myVar = myModule.myVar;

correct

const myModule = rewire('./myModule'); const myVar = myModule.__get__('myVar');

__get__ is a method that retrieves private variables; direct access won't work.

__with__

wrong

myModule.__with__('variable', mockValue);

correct

myModule.__with__({ variable: mockValue })(() => { ... });

__with__ accepts an object of overrides and returns a function to execute.

Quickstart

Shows how to configure webpack with RewirePlugin and use rewire to get/set private variables.

// webpack.config.js
var RewirePlugin = require('rewire-webpack');
module.exports = {
  entry: './index.js',
  output: { path: __dirname + '/dist', filename: 'bundle.js' },
  plugins: [
    new RewirePlugin()
  ]
};

// src/module.js
var privateVar = 'secret';
function getPrivate() { return privateVar; }
module.exports = { getPrivate: getPrivate };

// test.js (browser bundle)
var rewire = require('rewire');
var myModule = rewire('./module.js');
console.log(myModule.__get__('privateVar')); // 'secret'
myModule.__set__('privateVar', 'mocked');
console.log(myModule.getPrivate()); // 'mocked'