alexxnica / identity-obj-proxy

An identity object using ES6 proxies. Useful for mocking webpack imports like CSS Modules.

identity-obj-proxy

An identity object using ES6 proxies. Useful for mocking webpack imports. For instance, you can tell Jest to mock this object as imported CSS modules; then all your className lookups on the imported styles object will be returned as-is.

npm install identity-obj-proxy

Real world example Wait what does that even mean

tl;dr

For a React component like

import React, { Component } from 'react';

import styles from './App.css'; // CSS Modules here

export default class App extends Component {
  render() {
    return (
      <div className={styles.root}>
        <h1 className={styles.hello}>Hello, world!</h1>
      </div>
    );
  }
}

we can generate a snapshot as below (notice that the class names get correctly mocked):

exports[`test App renders correctly 1`] = `
<div
  className="root">
  <h1
    className="hello">
    Hello, world!
  </h1>
</div>
`;

For more information, please take a look at https://github.com/keyanzhang/jest-css-modules-example/ and https://facebook.github.io/jest/docs/tutorial-webpack.html.

Requirement

No flag is required for Node.js v6.*; use node --harmony_proxies flag for v5.* and v4.*.

Example

import idObj from 'identity-obj-proxy';
console.log(idObj.foo); // 'foo'
console.log(idObj.bar); // 'bar'
console.log(idObj[1]); // '1'