Test Driven Development with JavaScript

测试驱动开发(TDD)

什么是TDD

TDD 是敏捷开发中的一项核心实践和技术，及方法论
TDD的原理是在开发功能代码之前，先编写单元测试用例代码
TDD 是 XP（Extreme Programming）的核心实践

Kent Beck

1999. Extreme Programming Explained: Embrace Change

WHY？

为什么TDD

传统编码

TDD编码

需求分析，想不清楚细节，管他呢，先开始写

需求细节不明确，跟PM确认

确认几次终于写完所有逻辑

运行起来测试一下，靠，果然不工作，调试

调试好久终于工作了

转测试，QA 测出 bug，debug，打补丁

终于，代码可以工作了

一看代码烂的像坨屎，不敢动，动了还得手工测试

传统编码

先分解任务，分离关注点, Tasking

列 Example，用实例化需求，澄清需求细节

写测试，只关注需求，程序的输入输出，不关心中间过程

写实现，不考虑别的需求，用最简单的方式满足当前需求即可

重构，用手法消除代码里的坏味道, Bad Smell

写完，手动测试一下，基本没什么问题，有问题补个用例，修复

转测试，小问题，补用例，修复

代码整洁且用例齐全，信心满满地提交

传统编码

TDD编码

如何TDD

测试失败

➜  banma_fe_starfire git:(feature/PSFECD-97) ✗ npm run test:unit

> banma_page@1.0.0 test:unit /Users/songyang/code/banma/banma_fe_starfire
> mocha --require babel-core/register ./static/**/*.spec.js



  #dateUtils
    #toDuration
      ✓ should return formatted date string from seconds
    #toRelativeDate
      1) should display relative date without time
      ✓ should display relative date with time


  2 passing (31ms)
  1 failing

  1) #dateUtils
       #toRelativeDate
         should display relative date without time:

      AssertionError: expected '09:09' to equal '09:090'
      + expected - actual

      -09:09
      +09:090

测试成功

➜  banma_fe_starfire git:(feature/PSFECD-97) ✗ npm run test:unit

> banma_page@1.0.0 test:unit /Users/songyang/code/banma/banma_fe_starfire
> mocha --require babel-core/register ./static/**/*.spec.js



  #dateUtils
    #toDuration
      ✓ should return formatted date string from seconds
    #toRelativeDate
      ✓ should display relative date without time
      ✓ should display relative date with time


  3 passing (20ms)

工具与框架

describe('#dateUtils', () => {
  describe('#toDuration', () => {
    it('should return formatted date string from seconds', () => {
      toDuration(59).should.equal('59秒')
      toDuration(60).should.equal('1分0秒')
      toDuration(3600).should.equal('1时0分0秒')
      toDuration(7261).should.equal('2时1分1秒')
    })
  })

  describe('#toRelativeDate', () => {
    let clock
    beforeEach(() => {
      clock = sinon.useFakeTimers(now.getTime())
    })

    afterEach(() => {
      clock.restore()
    })

    it('should display relative date without time', () => {
      toRelativeDate(lastYear.getTime() / 1000).should.equal('2017-05-16')
      // ...
    })

    it('should display relative date with time', () => {
      toRelativeDate(yesterday.getTime() / 1000, withTime).should.equal('昨天 09:09')
      // ...
    })
  })
})

BDD测试风格

$ mkdir workshop
$ cd workshop
$ npm init
$ npm i -S mocha
$ mkdir test
$ touch test/test.js

{
  "name": "workshop",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "mocha"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "mocha": "^5.2.0"
  }
}

安装指南

const assert = require('assert')

describe('my test cases', () => {
  it('it should be true', () => {
    assert.equal(1 === 1, true, '1 === 1 should be true')
  })
})