javascript - 如何在 Jest 测试中重新模拟库？

Question

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', () => {
    ?????
  })
})

在 prepareRequestHeaders 中，我导入 ../redux/storeConfigure

如何使用其他实现重新模拟../redux/storeConfigure？

编辑:

/* 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

Answer 1

类似这样的事情应该可以解决:

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
  })
})

当您分配给 Jest 模拟 (jest.fn()) 时，您可以随时更改其返回值。由于模拟提升，它的名称必须以 mock 开头