在 Jest 中模擬文件加載期間調用的函數

Question

我有一個文件，我正在嘗試對其進行單元測試。 我希望通過調用feathers和auth庫方法以及測試導出的login和logout方法調用適當的庫方法來測試API 對象是否是創建的。

我想模擬對庫方法的所有調用，以便對該文件進行單元測試。

這是我到目前為止：

api.js

import feathers from '@feathersjs/feathers'
import auth from '@feathersjs/authentication-client'

export const DEFAULT_TIMEOUT = 30

const api = feathers()
api.configure(auth({ storage: window.localStorage, timeout: DEFAULT_TIMEOUT * 1000 }))

const login = async (credentials) => {
  return api.authenticate(credentials)
}

const logout = async () => {
  return api.logout()
}

export default { login, logout }

api.test.js

import feathers from '@feathersjs/feathers'
import auth from '@feathersjs/authentication-client'

import api, { DEFAULT_TIMEOUT } from './api'

const mockFeathers = {
  configure: jest.fn(),
  authenticate: jest.fn(),
  logout: jest.fn()
}
jest.mock('@feathersjs/feathers', () => jest.fn(() => mockFeathers))
jest.mock('@feathersjs/authentication-client', () => jest.fn(() => 'AUTH'))

describe('helpers/api', () => {
  it('creates a Feathers app with authentication', () => {
    expect(feathers).toHaveBeenCalled()
    expect(auth).toHaveBeenCalledWith({
      storage: window.localStorage,
      timeout: DEFAULT_TIMEOUT * 1000
    })

    expect(mockFeathers.configure).toHaveBeenCalledWith('AUTH')
  })

  describe('login', () => {
    it('authenticates with the Feathers app', async () => {
      const loginResult = { loggedIn: true }
      mockFeathers.authenticate.mockImplementationOnce(() => loginResult)

      const credentials = { email: 'user@example.com', password: 'password' }
      const result = await api.login(credentials)

      expect(mockFeathers.authenticate).toHaveBeenCalledWith(credentials)
      expect(result).toEqual(loginResult)
    })
  })

  describe('logout', () => {
    it('logs out from the Feathers app', async () => {
      await api.logout()

      expect(mockFeathers.logout).toHaveBeenCalled()
    })
  })
})

此失敗ReferenceError: mockFeathers is not defined ，因為它似乎api.js被加載（以及因此feathers調用的方法）之前mockFeathers定義。 我曾嘗試將import api行mockFeathers的定義下方，但這並沒有什么區別。

如何在加載api.js文件之前api.js feathers()調用的結果？

Answer 1

我確實通過完全刪除導入並require在beforeAll塊中api.js來實現這一點。 這有效，但對我來說似乎有點混亂，如果您從require d 文件中有多個單獨的導入，則無法很好地擴展。

api.test.js

// Remove the import line.
//import api, { DEFAULT_TIMEOUT } from './api'

describe('helpers/api', () => {
  let api, DEFAULT_TIMEOUT
  beforeAll(() => {
    // Require the file here so that the mock has time to be defined.
    ;({ default: api, DEFAULT_TIMEOUT } = require('./api'))
  })

  // ...
})

Answer 2

似乎是測試失敗的兩個import語句..請嘗試刪除兩者：

import feathers from '@feathersjs/feathers'
import auth from '@feathersjs/authentication-client'

並保留模擬語句。