React-native-fcm: Jest not properly mocking library

[Keksike]

When trying to run tests on Jest for my app which uses react-native-fcm I get error:

Invariant Violation: Native module cannot be null.

      at invariant (node_modules/fbjs/lib/invariant.js:44:15)
      at new NativeEventEmitter (node_modules/react-native/Libraries/EventEmitter/NativeEventEmitter.js:32:1)
      at Object.<anonymous> (node_modules/react-native-fcm/index.js:3:18)
      at Object.<anonymous> (app/components/MyComponent.js:6:21)

(MyComponent.js:6 is import FCM from 'react-native-fcm';)

Version info:

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This problem has been earlier reported, but closed as https://github.com/evollu/react-native-fcm/issues/435

[evollu]

shouldn't jest just mock out the whole FMC package?
Does this issue happen for other 3rd party react native packages?

[Keksike]

I didn't get this issue for other 3rd party react-native packages in my project, which included e.g.:

    "react-native-communications": "^2.2.1",
    "react-native-config": "^0.3.1",
    "react-native-google-analytics-bridge": "^5.0.1",
    "react-native-maps": "^0.15.2",
    "react-native-menu": "^0.20.2",
    "react-native-permissions": "^1.0.0"

[evollu]

try replace this like https://github.com/evollu/react-native-fcm/blob/master/index.js#L3
with const EventEmitter = new NativeEventEmitter(NativeModules.RNFIRMessaging || {});

[Keksike]

Hey @evollu,

That seemed to fix the problem.

Thank you for the temporary fix!

[evollu]

will update code
fixed in 9.7.2