In tests, stateless components dont have displayName

Is this a bug report?

Not sure if it’s CRA configuration issue or Jest bug.

Can you also reproduce the problem with npm 4.x?

Yes (node v7, npm v4).

Which terms did you search for in User Guide?

anonymous, displayname (also searched from issues).

Environment

1. node -v: v8.4.0
2. npm -v: 5.3.0
3. yarn --version: 0.27.5
4. npm ls react-scripts: 1.0.12

Then, specify:

1. Operating system: Ubuntu 17.04
2. Browser and version (if relevant):

Steps to Reproduce

1. Fresh install of CRA

2. Add a stateless component like this (Hello.js)

import React from 'react'
import PropTypes from 'prop-types'

export const Hello = ({name}) => (<div>Hi {name}</div>)

Hello.propTypes = {
  name: PropTypes.node.isRequired,
}

export default Hello

1. Add a test (Hello.spec.js)

import React from 'react';
import ReactDOM from 'react-dom';
import Hello from './Hello'

describe('<Hello />', () => {
  it('renders', () => {
    const div = document.createElement('div');
    ReactDOM.render(<Hello />, div);
  })
})

1. Run tests, yarn test

Expected Behavior

PropTypes error should show a component name, Hello, like development build does (yarn start).

Actual Behavior

Warning doesnt have a component name, shows <<anonymous>> instead:

console.error node_modules/fbjs/lib/warning.js:35
      Warning: Failed prop type: The prop `name` is marked as required in `<<anonymous>>`, but its value is `undefined`.
          in Unknown (at Hello.spec.js:8)

Reproducible Demo

Copy & paste snippets from repro steps.

[loganfsmyth]

Sounds like probably https://github.com/babel/babel/issues/5630

[gaearon]

Seems like both referenced PRs got merged so eventually fixes will propagate.