Jest Mock - 将值插入测试文件

Question

我在将值插入被测文件时遇到问题：

import device from '../device'

let execute = () => {
  if (device.isAndroid()) {
    return true
  else {
    return false
  }
}

现在是测试文件：

jest.mock('../device')
import device from '../device'

describe('when the device is Android', () => {
  let device

  beforeEach(() => {
    device = jest.fn().mockImplementation(() => {
      return { 
        isAndroid: () => { return true } 
      }
    })
  })

  it('returns true', () => {
    let results = execute()
    expect(result).toEqual(true)
  })
})

测试失败并返回false。我做错了什么？

Answer 1

你需要用一个玩笑的间谍来模拟'../device'，并在上面模拟实现：

jest.mock('../device', ()=>{return {isAndroid: jest.fn()}})
import device from '../device'

describe('when the device is Android', () => {

  beforeEach(() => {
    device.isAndroid.mockImplementation(() => true)
  })

  it('returns true', () => {
    let results = execute()
    expect(result).toEqual(true)
  })
})