为什么在玩笑中需要`module.exports`？ 我该如何避免呢？

Question

I've met the trouble when trying to test my react js code using jest framework.

Let say this is mine component:

# coffee/global_widget.coffee
@GlobalWidget = React.createClass
  render: ->
    <div className='row'>
      <div className='col-md-12'>
        <TerminalWidget />
      </div>
    </div>

# coffee/terminal_widget.coffee
@TerminalWidget = React.createClass
  render: ->
    <div>Hey! This is the terminal!</div>

So, I want to test it using jest .

jest.dontMock '../coffee/global_widget'

describe 'GlobalWidget', ->
  global.React = require('react/addons')
  GlobalWidget = require('../coffee/global_widget')
  TestUtils = React.addons.TestUtils

  globalWidgetForTest = TestUtils.renderIntoDocument(<GlobalWidget />)
  # body of the test

I have a trouble:

npm test

> terminal-ui@0.0.2 test /home/alex/my_project
> jest

Using Jest CLI v0.4.5
 FAIL  __tests__/global_widget-test.coffee (0.276s)
● GlobalWidget › it encountered a declaration exception
  - ReferenceError: GlobalWidget is not defined

If I append module.exports = @GlobalWidget to the coffee/global_widget.coffee , then I get TerminalWidget is not defined . What is module.exports= and why do I need to puts them for every component in my code?

Answer 1

It looks like jest doesnt have access to your global variables, so you need to export each file and require them as necessary.
you need to use module.exports because youre using the requirejs syntax with this line GlobalWidget = require('../coffee/global_widget') . What this does is isolate your code to prevent having a bunch of globally available code. this way, you import (using require ) and export (using module.exports = ... ) only the code you actually need. additionally, as in this case, it allows processes such as jest to gain access to files that are otherwise available.

if you absolutely dont want to use requirejs (which would be recommended to use) you can try adding them to your globals or fiddling with jests config to make these available prior to your test suite, though this will probably be more difficult than just exporting your modules