Jest: Jest React Native - Invariant Violation: Native module cannot be null.

[MechanicKim]

Do you want to request a feature or report a bug?
bug

What is the current behavior?
When I run 'npm run jest', I got an error like this.
Invariant Violation: Native module cannot be null.

  at invariant (node_modules/fbjs/lib/invariant.js:38:15)
  at Linking.NativeEventEmitter (node_modules/react-native/Libraries/EventEmitter/NativeEventEmitter.js:32:1)
  at new Linking (node_modules/react-native/Libraries/Linking/Linking.js:119:141)
  at Object.<anonymous> (node_modules/react-native/Libraries/Linking/Linking.js:191:16)
  at Object.get Linking [as Linking] (node_modules/react-native/Libraries/react-native/react-native.js:91:22)
  at Object.<anonymous> (node_modules/react-native-experimental-navigation/NavigationRootContainer.js:15:36)

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal repository on GitHub that we can npm install and npm test.

1. cd react-native-router-flux
2. npm install
3. cd Example
4. npm install
5. npm run jest

https://github.com/MechanicKim/react-native-router-flux

What is the expected behavior?
Pass the jest test and update snapshot

Run Jest again with --debug and provide the full configuration it prints. Please mention your node and npm version and operating system.
Darwin 16.1.0
node v7.2.0
npm v3.10.9

[cpojer]

Set the preset to "react-native" and remove jest-react-native. It isn't needed any more with 0.38!

[MechanicKim]

@cpojer I did it but I got same error.

2016-12-02 22:14 GMT+09:00 Christoph Pojer [e-mail]:

Closed #2208 https://github.com/facebook/jest/issues/2208.

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[cliedeman]

I am also getting this error.

Steps to reproduce:

• react-native init a fresh project with 0.39
• run jest, tests pass
• Add dependency "react-native-router-flux": "^3.37.0"
• Add import import { Router, Scene } from 'react-native-router-flux'
• run jest, get the above error

The current jest setup.js does not mock out Linking.

I was able to get past the error by adding

Linking: {
  addEventListener: jest.fn(),
  removeEventListener: jest.fn(),
  openURL: jest.fn(),
  canOpenURL: jest.fn(),
  getInitialURL: jest.fn(),
},

After AsyncLocalStorage {...},

The problematic line is const Linking = require('react-native').Linking; from the react-native-experimental-navigation fork that react-native-router-flux uses.

package.json:

{
    "name": "test",
    "version": "0.0.1",
    "private": true,
    "scripts": {
        "start": "node node_modules/react-native/local-cli/cli.js start",
        "test": "jest"
    },
    "dependencies": {
        "react": "15.4.1",
        "react-native": "^0.39.0",
        "react-native-router-flux": "^3.37.0"
    },
    "jest": {
        "preset": "react-native"
    },
    "devDependencies": {
        "babel-jest": "17.0.2",
        "babel-preset-react-native": "1.9.0",
        "jest": "17.0.3",
        "react-test-renderer": "15.4.1"
    }
}

@cpojer Is there any way to mock out react native Linking globally without duplicating the setup.js file?

[cliedeman]

Figured it out

Created a file jest/setup.js with the following content

jest.mock('Linking', () => {
  return {
    addEventListener: jest.fn(),
    removeEventListener: jest.fn(),
    openURL: jest.fn(),
    canOpenURL: jest.fn(),
    getInitialURL: jest.fn(),
  }
})

Add changed my package.json

...
"jest": {
    "preset": "react-native",
    "setupFiles": ["jest/setup.js"]
},
...

Although there has been some change behaviour because previously this mock was not required.

[rewieer]

I've got this problem as well on RN 38 with Jest 17.0.3. The problem is coming from NetInfo and react-native-router-flux. This is how i Implemented this from your solution :

jest.mock('Linking', () => {
  return {
    addEventListener: jest.fn(),
    removeEventListener: jest.fn(),
    openURL: jest.fn(),
    canOpenURL: jest.fn(),
    getInitialURL: jest.fn(),
  }
});

jest.mock('NetInfo', () => {
  return {
    isConnected: {
      fetch: () => {
        return new Promise((accept, resolve) => {
          accept(true);
        })
      }
    }
  }
});

[cwahlfeldt]

@cliedeman Worked me for me thanks! However I feel like RN or Jest needs to figure it out. :)

[rewieer]

I think it's more the job of the react-native preset to figure it out, rather than jest itself

[cpojer]

We merged this preset back into react-native; please send mocks and PRs directly there.

[rewieer]

I'll give it a shot when i'll have some time.

[hybrisCole]

the same thing happened to me, had to

jest.mock('PushNotificationIOS', () => ({
  addEventListener: jest.fn(),
  requestPermissions: jest.fn(),
}));

[gpminsuk]

Cleaner solution using __mocks__
Create __mocks__ directory next to __tests__ and place react-native.js with

const rn = require('react-native')
jest.mock('Linking', () => {
  return {
    addEventListener: jest.fn(),
    removeEventListener: jest.fn(),
    openURL: jest.fn(),
    canOpenURL: jest.fn(),
    getInitialURL: jest.fn(),
  }
})
module.exports = rn

[JeroenNelen]

Edited; I had to refer to the file via "./jest/setup.js" since updating, before the "jest/setup.js" was working without any issues (I found the solution here: https://github.com/facebook/react-native/issues/11585)

---

Any update on this? I was using this workaround:
"jest": { "preset": "react-native", "setupFiles": [ "jest/setup.js" ], "collectCoverage": true, "verbose": true },

But since updating all my packages to the latest versions today, Jest keeps giving this error:
Error: Jest: Module "jest/setup.js" in the "setupFiles" option was not found.

Any clue why it can no longer find the file? It hasn't moved or anything.

Kind regards,

[alexxv]

@JeroenNelen I've managed to workaround this with prepending <rootDir>:
"jest": { "preset": "jest-react-native", "setupFiles": [ "<rootDir>/jest-setup.js" ] }

Ugly, but works.

[cpojer]

In Jest 18.1, doing ./jest-setup.js will be resolved from the location of package.json.

[rewieer]

Should there be a solution to mock custom components directly in jest ? A flow-typed like repository for example.

[cpojer]

That might be cool!

[andrewhl]

I have a similar issue. I have a saga that is importing:

import Camera from 'react-native-camera';

This throws the error:

 FAIL  js/sagas/App/__tests__/watchCheckDevicePermissions-test.js
  ● Test suite failed to run

    TypeError: Cannot read property 'Aspect' of undefined

      at Object.<anonymous> (node_modules/react-native-camera/index.js:254:78)
      at Object.<anonymous> (js/sagas/App/watchCheckDevicePermissions.js:26:95)
      at Object.<anonymous> (js/sagas/App/__tests__/watchCheckDevicePermissions-test.js:2:34)

I tried to define a Camera mock in ./js/jest/setup.js:

jest.mock('Camera', () => {
    return {
        Aspect: {}
    }
});

Which is required in package.json setupFiles. All my tests start throwing the error:

Cannot find module 'Camera' from 'setup.js'

I also get the Invariant error for other libraries. For example, Pusher. I get the Cannot find module warning if I try to mock Pusher:

jest.mock('Pusher', () => {
    return {
        addEventListener: jest.fn(),
        removeEventListener: jest.fn()
    }
});

This is my jest config in package.json:

  "jest": {
    "preset": "react-native",
    "setupFiles": ["./js/jest/setup.js"],
    "transformIgnorePatterns": [
      "node_modules/(?!react-native||@shoutem)"
    ]
  },

React version: 15.4.2
React-native version: ^0.40.0
Jest version: ^19.0.0

[andrewhl]

I got it working, but had to add the following to my jest/setup.js file (to get my saga tests running):

jest.mock('PushNotificationIOS', () => ({
    addEventListener: jest.fn(),
    requestPermissions: jest.fn(),
}));
jest.mock('react-native', () => ({
    NetInfo: {
        addEventListener: jest.fn(),
        fetch: () => {
            return {
                done: jest.fn()
            }
        }
    },
    NativeModules: {
        RNPasscodeStatus: {
            supported: jest.fn(),
            status: jest.fn(),
            get: jest.fn()
        }
    },
    Dimensions: {
        get: () => ({
            width: jest.fn(),
            height: jest.fn()
        })
    },
}));
jest.mock('react-native-camera', () => {
});

Is this overkill? Also, I need to explicitly call jest.unmock('react-native') in my component tests.

[morungos]

Hmmm, I've had to amend these slightly. I'm using react-native-push-notification version 2.2.1.

jest.mock('PushNotificationIOS', () => {
  return {
    addEventListener: jest.fn(),
    requestPermissions: jest.fn(() => Promise.resolve()),
    getInitialNotification: jest.fn(() => Promise.resolve()),
  }
});

Because requestPermissions and getInitialNotification seem to return a promise now. Would love this to be stable.

[DZuz14]

For anyone having issues with react-native-router-flux, I had this problem today, and went with this solution https://github.com/facebook/jest/issues/2208#issuecomment-269847217

Quick and painless.

[kyangy]

@andrewhl Were you able to successfully mock pusher? Im having trouble getting my tests fixed because of the Invariant Violation: Native module cannot be null. error

[andrewhl]

@kyangy I think in the end I didn't need to. The library that was causing problems was react-native-push-notification, which I mocked as follows:

jest.mock('react-native-push-notification', () => {
    return {
        addEventListener: jest.fn(),
        removeEventListener: jest.fn(),
        requestPermissions: jest.fn(),
        configure: jest.fn()
    }
});

Have you tried creating a jest/__mocks__/pusher.js file that looks something like:

module.exports = {
    // whatever methods or properties are being accessed via the pusher object
}

I was able to narrow down exactly what libraries and methods needed to be mocked by systematically removing all imports from the component/file under test, and commenting out a lot of code, and reintroducing things one at a time. I mocked whatever caused the test to squawk.

[mierz00]

Has any one had the same issue with react-native-callkit ?

 Invariant Violation: Native module cannot be null.

      635 | }
      636 |
    > 637 | export default function app(state = initialState, action) {
      638 |   switch (action.type) {
      639 |     case INIT:
      640 |       return {

      at invariant (node_modules/fbjs/lib/invariant.js:42:15)
      at new NativeEventEmitter (node_modules/react-native/Libraries/EventEmitter/NativeEventEmitter.js:37:1)
      at Object.<anonymous> (node_modules/react-native-callkit/index.js:10:23)

I've tried the solutions above but I gather I'm not mocking the right functions. Does any one have any ideas on what exactly should be mocked?

[ps0305]

getting same error message after implementing react-native-gps-state module into the project.can someone please suggest how to mock one.

[thymikee]

jest.mock('react-native-gps-state', () => {
  return {
    nativeMethodToMock: jest.fn(),
    anotherNativeMethod: jest.fn()
  }
})

[iconicsammy]

came across this when using react-navigation-drawer. Created __mocks__/react-navigation-drawer.js with

jest.mock('react-navigation-drawer', () => {
    return {
      addEventListener: jest.fn(),
      createDrawerNavigator: jest.fn(),
    }
  });

But then the error gets replaced with createDrawerNavigator is not a function. Am I doing something wrong?