模拟 Jest 测试

以下是非常简单的Jest测试代码。

expect(3).toBe(3) // ✅
expect(4).toBe(3) // ❌

我们可以通过not将其反过来。

expect(3).not.toBe(3) // ❌
expect(4).not.toBe(3) // ✅

请实现myExpect()并支持toBe()及not.

✨ 如果考虑到代码的健壮性，如何避免硬编码？

题目模版

myExpect.js

/**
 * @param {any} input
 * @returns {true | false}
 */
export default function myExpect(input) {

}

myExpect.ts

interface ExpectResult<T> {
  toBe: (checker: T) => boolean
  readonly not: ExpectResult<T>
}

export default function myExpect<T>(input: T): ExpectResult<T> {

}

测试代码

myExpect.spec.js

import { describe, expect, it } from 'vitest'
import myExpect from './myExpect'

describe('day18-myExpect', () => {
  const theSameObject = {}

  it.each([
    [3, 3, true],
    [1, 1, true],
    [Symbol(1), Symbol(1), false],
    [Symbol.for(1), Symbol.for(1), true],
    [+0, -0, false],
    [{}, {}, false],
    [theSameObject, theSameObject, true],
  ])('myExpect(%s).toBe(%s) 的结果应为 %s', (received, expected, result) => {
    expect(myExpect(received).toBe(expected)).toBe(result)
  })

  it.each([
    [3, 3, false],
    [1, 1, false],
    [Symbol(1), Symbol(1), true],
    [Symbol.for(1), Symbol.for(1), false],
    [{}, {}, true],
    [theSameObject, theSameObject, false],
  ])(
    'myExpect(%s).not.toBe(%s) 的结果应为 %s',
    (received, expected, result) => {
      expect(myExpect(received).not.toBe(expected)).toBe(result)
    },
  )
})

myExpect.spec.ts

import { describe, expect, it } from 'vitest'
import myExpect from './myExpect'

describe('day18-myExpect', () => {
  const theSameObject = {}

  it.each([
    [3, 3, true],
    [1, 1, true],
    [Symbol(1), Symbol(1), false],
    [Symbol.for('1'), Symbol.for('1'), true],
    [+0, -0, false],
    [{}, {}, false],
    [theSameObject, theSameObject, true],
  ])('myExpect(%s).toBe(%s) 的结果应为 %s', (received, expected, result) => {
    expect(myExpect(received).toBe(expected)).toBe(result)
  })

  it.each([
    [3, 3, false],
    [1, 1, false],
    [Symbol(1), Symbol(1), true],
    [+0, -0, true],
    [Symbol.for('1'), Symbol.for('1'), false],
    [{}, {}, true],
    [theSameObject, theSameObject, false],
  ])(
    'myExpect(%s).not.toBe(%s) 的结果应为 %s',
    (received, expected, result) => {
      expect(myExpect(received).not.toBe(expected)).toBe(result)
    },
  )
})

答案

类型	路径
JS 版本	problems/Day 18/answer.js
TS 版本	problems/Day 18/ts/answer.ts
Review	18.md