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  • mocha ☕️ simple, flexible, fun javascript test framework for node.js & the browser
  • chai-as-promised Extends Chai with assertions about promises.

demo 仓库

mocha 测试常见问题

常见的 promise、async/await、timeout 测试

// mocha-spec.js
const chai = require('chai')
const { expect, assert } = chai
const timeout = 5000
const delay = 1000

const p = (status, timeout = 100) =>
  new Promise((resolve, reject) => {
    const test = () => {
      if (status === 'fulfilled') {
        resolve(status)
      } else {
        reject(status)
      }
    }

    setTimeout(test, timeout)
  })

describe('demo', function () {
  it('promise', (done) => {
    p('fulfilled').then((res) => {
      expect(res).to.equal('fulfilled')
      done()
    })
  })

  it('promise multi', function (done) {
    // 重新设置超时时间 > 执行时间
    this.timeout(5 * timeout)

    // done 会在 2200 后执行。超过了默认 2000
    p('fulfilled').then((res) => {
      expect(res).to.equal('fulfilled')

      p('fulfilled').then((res) => {
        expect(res).to.equal('fulfilled')
        done()
      })
    })
  })

  it('promise multi with delayed', function (done) {
    // 重新设置超时时间，如果不设置，则报错
    // 'Error: Timeout of 2000ms exceeded. For async tests and hooks, ensure "done()" is called;if returning a Promise, ensure it resolves'
    this.timeout(timeout)

    // done 会在 2200 后执行。超过了默认 2000
    const test = () =>
      p('fulfilled').then((res) => {
        expect(res).to.equal('fulfilled')

        p('fulfilled').then((res) => {
          expect(res).to.equal('fulfilled')
          done()
        })
      })

    setTimeout(test, delay)
  })

  it('timeout', () => {
    this.timeout(1000)
    assert.ok(true)
  })

  it('timeout demo', function (done) {
    this.timeout(500)
    setTimeout(done, 300)
  })

  it('timeout with done', function (done) {
    this.timeout(timeout)
    const test = () => {
      assert.ok(true)
      done()
    }
    setTimeout(test, delay)
  })

  it('timeout with async done', function (done) {
    this.timeout(timeout)

    const test = async () => {
      const res = await p('fulfilled')
      expect(res).to.equal('fulfilled')
      done()
    }

    setTimeout(test, delay)
  })

  it('timeout with promise done', function (done) {
    this.timeout(timeout)

    const test = () => {
      p('rejected').catch((e) => {
        expect(e).to.equal('rejected')
        done()
      })
    }
    setTimeout(test, delay)
  })

  it('timeout with promise catch done', function (done) {
    this.timeout(timeout)

    const test = () => {
      p('rejected').catch((e) => {
        expect(e).to.equal('rejected')
        done()
      })
    }
    setTimeout(test, delay)
  })

  it('timeout with async catch done', function (done) {
    this.timeout(timeout)

    const test = async () => {
      try {
        const multiPromise = [
          await p('fulfilled'),
          await p('fulfilled'),
          await p('fulfilled'),
        ]

        for (let p of multiPromise) {
          expect(p).to.equal('fulfilled')
        }

        done()
      } catch (e) {
        done(e)
      }
    }

    setTimeout(test, delay)
  })
})

如果测试的结果返回的是一个 Promise，更多测试用例参考chai-as-promised/test

// chai setup
// https://github.com/domenic/chai-as-promised/blob/master/test/support/setup.js
const chai = require('chai')
const chaiAsPromised = require('chai-as-promised')

chai.should()
chai.use(chaiAsPromised)

const { expect, assert } = chai

describe('demo', function () {
  // 参考 官方 demo
  // https://github.com/domenic/chai-as-promised/blob/master/test/should-eventually.js
})