Question

我有一个测试，我试图在两种不同的情况下模拟一个组件。当我使用jest.fn时。看起来第一个测试只是从第二个测试中获取值。

describe('tests', () => {
  let sampleArray = new Array()
  Array.prototype.test = function() {
    return this.innerArray()
  }
  describe('empty', () => {
    sampleArray.innerArray = jest.fn(() => [])
    it('testArray is empty', () => {
      expect(sampleArray.test().length).toEqual(0)
    })
  })

  describe('not empty', () => {
    sampleArray.innerArray = jest.fn(() => ['test'])
    it('testArray is not empty', () => {
      console.log(sampleArray.innerArray())
      expect(sampleArray.test().length).toEqual(1)
    })
  })
})

当我console.log时，我得到了我希望来自innerArray的数组，但它看起来似乎没有使用它。

FAIL  test/sample.test.js
  tests
    empty
      ✕ testArray is empty (8ms)
    not empty
      ✓ testArray is not empty (4ms)

  ● tests › empty › testArray is empty

    expect(received).toEqual(expected)

    Expected value to equal:
      0
    Received:
      1

编辑：如果我将它放在it范围内，它就可以了。但为什么我不能在describe范围内这样做？

describe('tests', () => {
  let sampleArray = new Array()
  Array.prototype.test = function() {
    return this.innerArray()
  }
  describe('empty', () => {
    it('testArray is empty', () => {
      sampleArray.innerArray = jest.fn(() => [])
      console.log(sampleArray.innerArray())
      expect(sampleArray.test().length).toEqual(0)
    })
  })

  describe('not empty', () => {
    it('testArray is not empty', () => {
      sampleArray.innerArray = jest.fn(() => ['test'])
      expect(sampleArray.test().length).toEqual(1)
    })
  })//works

Answer 1

除非您特别希望在所有测试中共享数组，否则应按如下方式进行设置：

Array.prototype.test = function() {
  return this.innerArray()
}

describe('tests', () => {
  let sampleArray

  beforeEach(() =>
    sampleArray = new Array()
  })

  // tests...
});

在模拟函数时在Jest中确定范围

1 个答案: