Jest setup not valid when importing ES6 modules

Bug

When importing functions with ES6 modules and running jest tests, NativeModules.RNDeviceInfo is not defined.

Environment info

React native info output:

info Fetching system and libraries information...
System:
    OS: macOS 10.15.1
    CPU: (8) x64 Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHz
    Memory: 1.27 GB / 16.00 GB
    Shell: 2.7.1 - /usr/local/bin/fish
  Binaries:
    Node: 10.14.0 - ~/.config/fnm/bin/node
    Yarn: 1.17.3 - /usr/local/bin/yarn
    npm: 6.9.0 - /usr/local/bin/npm
    Watchman: 4.9.0 - /usr/local/bin/watchman
  SDKs:
    iOS SDK:
      Platforms: iOS 13.2, DriverKit 19.0, macOS 10.15, tvOS 13.2, watchOS 6.1
  IDEs:
    Xcode: 11.3/11C29 - /usr/bin/xcodebuild
  npmPackages:
    react: 16.8.6 => 16.8.6
    react-native: 0.60.4 => 0.60.4
  npmGlobalPackages:
    create-react-native-app: 2.0.2
    react-native-git-upgrade: 0.2.7

Library version: 5.4.0

Steps To Reproduce

1. Install the library
2. Use in a component and create a jest test for it.
3. Use the device info library, importing a function as an ES6 module. …

Describe what you expected to happen:

1. Test to not error for NativeModules error

Reproducible sample code

[jefflewis]

Yea, I couldn’t figure out why it didn’t work. Maybe a simple DX approach would be to add a “Testing with Jest” section to the readme that has the mock ready for copy/pasting? I grabbed the export from that commit and dropped it into my project and was ready to go.

It would still require some additional maintenance, but would maybe encourage some helpful PRs to update the readme instead of Issues that complain about it failing the test?

Either way, this issue should stay closed. Thanks for taking a look!

[mikehardy]

PRs to the README happily accepted 😅 🙏