如何使用 SinonJs 监视异步调用的数量而无需等待答案

【问题标题】：How to use SinonJs to spy on number of async calls without await如何使用 SinonJs 监视异步调用的数量而无需等待
【发布时间】：2021-05-09 10:59:03
【问题描述】：

在下面的示例中，我有两个函数 doTask 和 doSubTask。两者都是异步的，但是由于某些业务需要，我需要使用不同的参数触发并忘记 doSubTask 两次

const wait = ms => new Promise(resolve => setTimeout(resolve, ms))

const doTask = async (taskId) => {
  await wait(taskId)
  doSubTask(taskId * 3)
  doSubTask(taskId * 5)
  console.log('end task :' + taskId)
}

const doSubTask = async (subTaskId) => {
  await wait(subTaskId)
  console.log('end subTask :' + subTaskId)
}

doTask(2000)

如何为 doTask 编写测试用例，并断言 doSubTask 已被调用两次？

这是一个代码示例，你可以在runkit.com上运行它

require("@fatso83/mini-mocha").install()

const sinon = require("sinon@7.5.0")
const referee = require("@sinonjs/referee")
const chai = require('chai')
chai.use(require('sinon-chai'))
const expect = chai.expect

const wait = ms => new Promise(resolve => setTimeout(resolve, ms))

const doTask = async (taskId) => {
  await wait(taskId)
  doSubTask(taskId * 3)
  doSubTask(taskId * 5)
  console.log('end task :' + taskId)
}

const doSubTask = async (subTaskId) => {
  await wait(subTaskId)
  console.log('end subTask :' + subTaskId)
}

const app = {
  doTask,
  doSubTask,
}

describe("stub", function () {
  it("doSubTask should be called twice", async function () {
    const doSubTaskSpy = sinon.spy(app, 'doSubTask')
    
    await doTask(2000)
    
    expect(doSubTaskSpy).to.be.calledTwice()
  })
})

上述代码的输出是：

stub
end task :2000
❌ doSubTask should be called twice (Failed with: "expecte…e been called exactly twice, but it was called 0 times")
end subTask :6000
end subTask :10000

【问题讨论】：

标签： javascript async-await mocha.js chai sinon

【解决方案1】：

我们应该使用rewire 包来要求模块和存根doSubTask 函数。此外，我们应该使用this way来使用假计时器，并在您同时使用promise和setTimeout时将时间提前。

例如

index.js:

const wait = (ms) => new Promise((resolve) => setTimeout(resolve, ms));

const doTask = async (taskId) => {
  await wait(taskId);
  doSubTask(taskId * 3);
  doSubTask(taskId * 5);
  console.log('end task :' + taskId);
};

const doSubTask = async (subTaskId) => {
  await wait(subTaskId);
  console.log('end subTask :' + subTaskId);
};

const app = {
  doTask,
  doSubTask,
};

module.exports = app;

index.test.js:

const rewire = require('rewire');
const sinon = require('sinon');

describe('stub', function () {
  let clock;
  before(() => {
    clock = sinon.useFakeTimers();
  });
  after(() => {
    clock.restore();
  });
  it('doSubTask should be called twice', async function () {
    const doSubTaskStub = sinon.stub();
    const mod = rewire('./');
    mod.__set__('doSubTask', doSubTaskStub);
    const promise = mod.doTask(2000);
    clock.tick(2010);
    await promise;
    sinon.assert.calledTwice(doSubTaskStub);
    sinon.assert.calledWithExactly(doSubTaskStub, 6000);
    sinon.assert.calledWithExactly(doSubTaskStub, 10000);
  });
});

测试结果：

  stub
end task :2000
    ✓ doSubTask should be called twice (738ms)


  1 passing (743ms)

----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |   84.62 |      100 |      75 |   81.82 |                   
 index.js |   84.62 |      100 |      75 |   81.82 | 11-12             
----------|---------|----------|---------|---------|-------------------

【讨论】：