使用Jest模拟命名的导入 [英] Using Jest to mock named imports

问题描述

我有一个'notifications.js'模块，看起来像这样:

I have a 'notifications.js' module that looks a bit like this:

import { Notifications, Permissions } from 'expo'

export function setLocalNotification(storage = AsyncStorage) {
  return storage
    .getItem(NOTIFICATION_KEY)
    .then(JSON.parse)
    .then(data => {
      if (data === null) {
        return Permissions.askAsync(
          Permissions.NOTIFICATIONS
        ).then(({ status }) => {
          if (status === 'granted') {
            Notifications.cancelAllScheduledNotificationsAsync()
            ...etc.

在我的测试中，我想模拟权限"和通知"，以便可以在notifications.spec.js中执行以下操作:

In my test, I want to mock Permissions and Notifications so I can do something like this in notifications.spec.js:

import { setLocalNotification } from './notifications'
import mockAsyncStorage from '../mock/AsyncStorage'

it('correctly cancels pending notifications', done => {
  setLocalNotification(mockAsyncStorage).then(done())
  expect(Permissions.askAsync).toBeCalled()
  expect(Notifications.cancelAllScheduledNotificationsAsync)
    .toBeCalled()
})

我已经尝试过使用jest.mock和jest.setMock进行各种操作，但似乎无法正常工作.如何以所需的方式模拟这些命名的导入?例如，我已经尝试过:

I've tried various things using jest.mock and jest.setMock but I can't seem to get this working. How do I go about mocking these named imports in the desired way? For instance, I've tried this:

jest.setMock('Permissions', () => ({
  askAsync: jest
    .fn()
    .mockImplementationOnce(() => ({ status: 'granted' }))
}))

但这不起作用.抛出

'module Permissions cannot be found from notifications.spec.js'

如果我尝试模拟整个expo模块，则模拟的函数expect().toBeCalled()返回false.

And if I try to mock the entire expo module, the mocked functions expect().toBeCalled() returns false.

推荐答案

您必须模拟模块'expo'

jest.mock('expo', ()=>({
  Permissions: {
     askAsync: jest.fn()
  }
}))

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