npm test fails with assets imported from node_modules folder

[robcaldecott]

I have published a number of in-house components that package up CSS and images so they can be included in a Webpack project like this:

import MyComponent from 'my-component'
import 'my-component/css/Styles.css'
import logo from 'my-component/img/CorporateLogo.png'

This has worked great with CRA and my apps run and build correctly.

However, any attempt to test code that includes CSS/images in this way with CRA 0.4.1 will fail - almost as if testing treats anything imported from node_modules as JavaScript.

e.g. when running a test of a component that imports a PNG from node_modules/my-component/img:

 FAIL  src\App.test.js
  ● Test suite failed to run

    C:\Users\<user>\Projects\my-app\node_modules\my-component\img\logo.png:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){�PNG
                                                                                             ^
    SyntaxError: Unexpected token ILLEGAL

      at transformAndBuildScript (node_modules\react-scripts\node_modules\jest-runtime\build\transform.js:284:10)
      at Object.<anonymous> (src\App.js:3:38)
      at Object.<anonymous> (src\App.test.js:3:38)

Any ideas or workarounds would be welcome.

[robcaldecott]

On further investigation this appears to be a problem with scopes. We are publishing packages to a private npm server and use scoping to avoid any clashes and to indicate this is a special package. So a sample package name may be:

@mycompany/my-component

https://docs.npmjs.com/private-modules/intro#setting-up-your-package

When you npm install the above it will end up in node_modules/@mycompany/my-component. This seems to be breaking the Jest config which then tries to actually import the assets as JS.

Further tests show it's that pesky @ sign that seems to break Jest. If I remove it from the folder name in node_modules then it will work OK.

[gaearon]

Can you please file this in Jest repo and link to this issue? Thank you!

[gaearon]

cc @cpojer

[fson]

The problem seems to be in the moduleNameMapper Jest configuration used in create-react-app. It only matches paths consisting of alphanumeric characters, so files with special characters like @ are not correctly stubbed in the tests. I'm making a pull request to fix this.

[gaearon]

Thanks @fson!

[gaearon]

This should be fixed in 0.4.2.
Please verify!