CODEWITHSUNDEEP
javascriptmockingjestjs
kspacja
kspacja

Reputation: 4874

How to remock libs in jest test?

jest.mock('../redux/storeConfigure', () => () => ({
  getState: () => ({ auth: { token: 'TEST_TOKEN' } })
}))

import { prepareRequestHeaders } from './fetch'

describe('prepareRequestHeaders', () => {
  it('returns header with Authorization if token is set', () => {
    expect(prepareRequestHeaders()['Authorization']).toBe('Bearer TEST_TOKEN')
  })

  it('returns header without Authorization if token is not set', () => {
    ?????
  })
})

In prepareRequestHeaders I import ../redux/storeConfigure

How to remock ../redux/storeConfigure with other implementation?

EDIT:

/* fetch.js */
import { store } from '../app'

export const prepareRequestHeaders = () => {
  const headers = {
    Accept: 'application/json',
    'Content-Type': 'application/json'
  }

  const { token } = store.getState().auth
  if (token) {
    headers['Authorization'] = `Bearer ${token}`
  }

  return headers
}

/* app.js */

import storeConfigure from './redux/storeConfigure'

export const store = storeConfigure()

/* Directories strucutre */
- redux
  - storeConfigure.js
- api
  - fetch.js
  - api.test.js
app.js

Upvotes: 0

Views: 1443

Answers (1)

SimenB
SimenB

Reputation: 7449

Something like this should work out:

let mockGetState;

jest.mock('../redux/storeConfigure', () => () => {
  mockGetState = jest.fn().mockReturnValue({ auth: { token: 'TEST_TOKEN' } })
  return { getState: mockGetState }
})

import { prepareRequestHeaders } from './fetch'

describe('prepareRequestHeaders', () => {
  it('returns header with Authorization if token is set', () => {
    expect(prepareRequestHeaders()['Authorization']).toBe('Bearer TEST_TOKEN')
  })

  it('returns header without Authorization if token is not set', () => {
    mockGetState.mockReturnValueOnce({auth: {token: 'SOMETHING_ELSE'}})
    // make your assertion
  })
})

When you assign to a Jest mock (jest.fn()) you can change its return value whenever you want. The name of it has to start with mock because of mock hoisting

Upvotes: 2

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