async testing with jest without extra squats

no_squat_testing.js

describe('sync', () => {
  test('value', () => expect(100500).toBe(100500))
  test('throw', () => expect(() => { throw 100500 }).toThrow('100500'))
})

describe('async', () => {
  describe('.resolves', () => {
    test('sleep', () => expect(
      new Promise(resolve => setTimeout(() => resolve(100500), 1))
    ).resolves.toBe(100500))

    test('instant', () => expect(
      new Promise(resolve => resolve(100500))
    ).resolves.toBe(100500))
    
    test('dummy', () => expect(
      Promise.resolve(100500)
    ).resolves.toBe(100500))
    
    test.skip('non promise', () => expect(100500).resolves.toBe(100500))
  })

  describe('.rejects', () => {
    test('instant', () => expect(
      new Promise((resolve, reject) => reject(100500))
    ).rejects.toBe(100500))
    
    test('dummy', () => expect(
      Promise.reject(100500)
    ).rejects.toBe(100500))
    
    test('throw', () => expect(
      new Promise(() => { throw 100500 })
    ).rejects.toBe(100500))
  })

  describe('callback', () => {
    var stat, promisify, callbackify
    beforeAll(() => ({ promisify, callbackify } = require('util')))
    beforeAll(() => ({ stat } = require('fs')))

    test('fs.stat as a promise', () => expect(
      promisify(stat)('.')
    ).resolves.toEqual(expect.anything()))
  })
})