Mocked module function with Jest is never called

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I have a really weird situation where my Jest tests are passing in my Windows 10 desktop and Macbook Pro, but they are not passing in 2 of my other friends' Windows 10 desktops.

Code that is being tested

import { addTerminalItem } from '../../store'
...
class LoginUser extends EventHandler {
  ...
  async handle () {
    if (this.isFromOauthRedirect) {
      try {
        await this._handleOauthRedirect()
      } catch (e) {
        addTerminalItem(new ErrorMessage(e.message))
      }
      return
    }

    if (await zaClient.isUserLoggedIn('testUserId')) {
      // TODO: user is already logged in, do something
    } else {
      const loginStartSecret = uuidv4()
      localStorage.setItem(LOGIN_START_SECRET, loginStartSecret)
      addTerminalItem(new LoginMessage(loginStartSecret))
    }
  }
  ...
}

export const loginUser = new LoginUser()

The testing code does the following:

  1. Adds invalid LOGIN_START_SECRET so that actual code throws exception entering the first catch.
  2. Subscribes the event handler to the event WELCOME_MESSAGE_RENDERED.
  3. Mocks the store.addTerminalItem module function.
  4. Publishes the event so the above async handle() function is triggered.
  5. Checks that the mocked function is called.
import * as store from '../../../store'
...
test('different login start secret in localstorage', async () => {
  localStorage.setItem(LOGIN_START_SECRET, 'different-secret')
  zaClient.login = jest.fn(() => true)
  store.addTerminalItem = jest.fn()

  await pubsub.publish(WELCOME_MESSAGE_RENDERED)

  expect(store.addTerminalItem).toHaveBeenCalledWith(expect.any(ErrorMessage))
  const errorMessage = store.addTerminalItem.mock.calls[0][0]
  expect(errorMessage.message).toBe(loginSecurityErrorMsg)
})

As I said on my computer it shows correctly that addTerminalItem function is called once with the correct argument on both machines I have at home. However this mocked function is never called and fails on 2 of my friends' machines. The actual error message they get is below:

expect(jest.fn()).toHaveBeenCalledWith(...expected)

Expected: Any<ErrorMessage>

Number of calls: 0

Here are the following things we tried so far:

  • Fresh git clone, yarn install, and yarn test. I pass and they don't.
  • With addTerminalItem mocked, we added a console.log inside addTerminalItem and it correctly doesn't log, but still 0 number of calls.
  • With addTerminalItem spyed, we added a console.log inside addTerminalItem and it correctly logs, but still 0 number of calls (this makes no sense to me)
  • We matched our yarn version.
  • We carefully debug stepped through the code to make sure all other things were working as expected.

If anyone could give us any pointers here it would be greatly appreciated.

jestjs javascript
1 Answers

Hard to be definitive without the code at hand, but try using jest.mock:

import {addTerminalItem} from "../../../store";

jest.mock('../../../store', () => ({
  addTerminalItem: jest.fn() 
));

//... stuff ...

test('different login start secret in localstorage', async () => {
  localStorage.setItem(LOGIN_START_SECRET, 'different-secret')
  zaClient.login = jest.fn(() => true)
  
  await pubsub.publish(WELCOME_MESSAGE_RENDERED)

  expect(addTerminalItem).toHaveBeenCalledWith(expect.any(ErrorMessage))
  const errorMessage = addTerminalItem.mock.calls[0][0]
  expect(errorMessage.message).toBe(loginSecurityErrorMsg)
})
user_1198860
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