“Define is not defined” in Jest when testing es6 m

问题:

I have a Jest test suite that fails to run because the component it's trying to test depends on a RequireJS module. Here's the error I'm seeing:

 FAIL  __tests__/components/MyComponent.test.js
  ● Test suite failed to run

    ReferenceError: define is not defined

      at Object.<anonymous> (node_modules/private-npm-module/utils.js:1:90)

The component has the following import:

import utils from 'private-npm-module';

And the private-npm-module is set up like so:

define('utils', [], function() {
  return {};
});

When MyComponent is transpiled with babel and run in the browser, the dependency operates correctly. This issue only affects the unit test. How can I get my test suite to run on a component with a RequireJS dependency?

I'm using babel-jest as my scriptPreprocessor in package.json's jest config. I'm using jest v0.15.1.

回答1:

So, RequireJS is not supported by Jest. In my particular case, it was easiest and most appropriate to mock my dependency at the top of MyComponent.test.js:

jest.mock('private-npm-module', () => {
  // mock implementation
})

import MyComponent from '../../components/MyComponent';

This way, when MyComponent is loaded, its dependency is already mocked, so it won't try to load the RequireJS module.

If you really do need to load your RequireJS module for your test, it may be possible to use jest's transform configuration to wrap your implementation in a RequireJS to ES6 converter.