I want to mock the node_module 'React Native Keychain' in React Native with Jest.

Following the docs I created a folder called __mocks__ and created a file called react-native-keychain.js in it.

Here is the code within the file:

export default jest.mock(react-native-keychain, () => {

  const token = abcdefghijklmnopqrstuvwxyz0123456789;

  const credentials = {

    username: session,

    password: token

  };

  return {

    setGenericPassword: jest.fn(

      (username, password) => new Promise((resolve, reject) => resolve(true)) // eslint-disable-line no-unused-vars

    ),

    getGenericPassword: jest.fn(() => new Promise((resolve, reject) => resolve(credentials))), // eslint-disable-line no-unused-vars

    resetGenericPassword: jest.fn(() => new Promise((resolve, reject) => resolve(true))) // eslint-disable-line no-unused-vars

  };

});

I then wrote my tests for the functions that use this library:

import * as keyChainFunctions from react-native-keychain;

import { setToken, getToken, clearToken } from ./secureStorage;



const token = abcdefghijklmnopqrstuvwxyz0123456789;



    describe(set token, () => {

      it(saves the token in the keychain, () => {

        expect.assertions(1);

        return setToken(token).then(res => {

          console.log(res);

          console.log(keyChainFunctions);

          expect(keyChainFunctions.setGenericPassword).toHaveBeenCalledWith(session, token);

        });

      });

    });

The problem is, that the test fails. I get the error message:

 FAIL  app/api/secureStorage/secureStorage.test.js

  set token

    ✕ saves the token in the keychain (42ms)



  ● set token › saves the token in the keychain



    expect(jest.fn())[.not].toHaveBeenCalledWith()



    jest.fn() value must be a mock function or spy.

    Received: undefined



      10 |       console.log(res);

      11 |       console.log(keyChainFunctions);

    > 12 |       expect(keyChainFunctions.setGenericPassword).toHaveBeenCalledWith(session, token);

         |                                                    ^

      13 |     });

      14 |   });

      15 | });



      at app/api/secureStorage/secureStorage.test.js:12:52

      at tryCallOne (node_modules/promise/lib/core.js:37:12)

      at node_modules/promise/lib/core.js:123:15

      at flush (node_modules/asap/raw.js:50:29)

 ● set token › saves the token in the keychain



    expect.assertions(1)



    Expected one assertion to be called but received zero assertion calls.



       6 | describe(set token, () => {

       7 |   it(saves the token in the keychain, () => {

    >  8 |     expect.assertions(1);

         |            ^

       9 |     return setToken(token).then(res => {

      10 |       console.log(res);

      11 |       console.log(keyChainFunctions);



      at Object.<anonymous> (app/api/secureStorage/secureStorage.test.js:8:12)

And the console.log() yield:

console.log app/api/secureStorage/secureStorage.test.js:10

    true



  console.log app/api/secureStorage/secureStorage.test.js:11

    { default:

       { addMatchers: [Function: addMatchers],



         advanceTimersByTime: [Function: advanceTimersByTime],

         autoMockOff: [Function: disableAutomock],

         autoMockOn: [Function: enableAutomock],

         clearAllMocks: [Function: clearAllMocks],

         clearAllTimers: [Function: clearAllTimers],

         deepUnmock: [Function: deepUnmock],

         disableAutomock: [Function: disableAutomock],

         doMock: [Function: mock],

         dontMock: [Function: unmock],

         enableAutomock: [Function: enableAutomock],

         fn: [Function: bound fn],

         genMockFromModule: [Function: genMockFromModule],

         isMockFunction: [Function: isMockFunction],

         mock: [Function: mock],

         requireActual: [Function: bound requireModule],

         requireMock: [Function: bound requireMock],

         resetAllMocks: [Function: resetAllMocks],

         resetModuleRegistry: [Function: resetModules],

         resetModules: [Function: resetModules],

         restoreAllMocks: [Function: restoreAllMocks],

         retryTimes: [Function: retryTimes],

         runAllImmediates: [Function: runAllImmediates],

         runAllTicks: [Function: runAllTicks],

         runAllTimers: [Function: runAllTimers],

         runOnlyPendingTimers: [Function: runOnlyPendingTimers],

         runTimersToTime: [Function: runTimersToTime],

         setMock: [Function: setMock],

         setTimeout: [Function: setTimeout],

         spyOn: [Function: bound spyOn],

         unmock: [Function: unmock],

         useFakeTimers: [Function: useFakeTimers],

         useRealTimers: [Function: useRealTimers] } }

What this tells me:
1. Either the mock works (because true is returned correctly) or the actual setGenericPassword function from React Native Keychain is being called.
2. For some reason, keychainfunctions is defined, but as the jest.mock object instead of the three mocked functions.

It feels like 1 and 2 contradict each other, if the mock works.
What am I doing wrong? Why does this mock not work? How can these weird console.log()s and failed tests be explained?

Bamse suggested in the comments to just export objects. This workaround works. I would still be interested how to correctly do it / what I did wrong.

const token = abcdefghijklmnopqrstuvwxyz0123456789;

const credentials = {

  username: session,

  password: token

};



export const setGenericPassword = jest.fn(

  (username, password) => new Promise((resolve, reject) => resolve(true)) // eslint-disable-line no-unused-vars

);



export const getGenericPassword = jest.fn(

  () => new Promise((resolve, reject) => resolve(credentials)) // eslint-disable-line no-unused-vars

);



export const resetGenericPassword = jest.fn(() => new Promise((resolve, reject) => resolve(true))); // eslint-disable-line no-unused-vars