How do I add React as a global whilst running unit tests?

Question

In my Rails project, I am using the react-rails gem, which does the following:

window.React = React;

This is pretty handy, but when I run unit tests using Jest, that global is not there and I get an error from the file containing the component I am testing saying that React is not defined.

If I define React in the component file using

import React from 'react';

Then it causes errors due to loading React twice.

How should I define a global React variable in my unit tests so they work?

maybe this is helpful? http://stackoverflow.com/questions/30233357/jest-react-how-to-use-global-object-in-unit-tests — jnes, Jan 11 '16 at 12:07
are you using webpack or babel? For you could set up a if/else branch to include the import line. [See this example with babel](https://babeljs.io/docs/plugins/transform-inline-environment-variables/) — enjoylife, Jan 12 '16 at 01:28

score 0 · Answer 1 · answered Mar 07 '16 at 15:40

In your test file, do:

import React from 'react'

describe('something',() => {
  window.React = React
  // so when you require() your component, window.React is already set
  var MyComponent = require('MyComponent').default

  it('does something', () => {
    // do something
  })
})

How do I add React as a global whilst running unit tests?

1 Answers1