index.test.js

import { find, deepCopy, isPromise } from './index.js'

it('find', () => {
  let list = [33, 22, 112, 222, 43]
  expect(
    find(list, a => {
      return a % 2 === 0
    })
  ).toBe(22)
})

it('deepCopy: nornal structure', () => {
  let original = {
    a: 1,
    b: 'string',
    c: true,
    d: null,
    e: undefined
  }
  let copy = deepCopy(original)

  expect(copy).toEqual(original)
})

it('deepCopy: nested structure', () => {
  let original = {
    a: {
      b: 1,
      c: [
        2,
        3,
        {
          d: 4
        }
      ]
    }
  }
  let copy = deepCopy(original)

  expect(copy).toEqual(original)
})

it('deepCopy: circular structure', () => {
  let original = {
    a: 1
  }
  original.circular = original

  let copy = deepCopy(original)

  expect(copy).toEqual(original)
})

it('isPromise', () => {
  let promise = new Promise(
    () => {},
    () => {}
  )
  let func = () => {}
  expect(isPromise(1)).toBe(false)
  expect(isPromise(promise)).toBe(true)
  expect(isPromise(func)).toBe(false)
})