Sinon.js：无法模拟 node.js 网络对象

Question

我对测试很陌生，所以这个问题可能很简单......但我仍然需要一些帮助：

我有一个 node.js 服务器：

const net = require("net");
const Canvas = require("./canvas");

server.on("connection", (socket) => {
  const canvas = (new Canvas(socket));
  ...
});

server.listen(8124);

在 canvas.js 文件中：

class Canvas {
  constructor(socket) {
    this.socket = socket;
  }
  
  disconnect() {
    this.socket.end();
    this.socket.destroy();
  }
}

我正在尝试测试断开功能，并尝试模拟套接字对象的方法：

const Canvas = ...
const expect = require("expect");
const sinon = require("sinon");

describe('Canvas', () => {
  const fakeSocket = {
    end: () => {},
    destroy: () => {},
    write: () => {},
  };

  let canvasObj;
  const mock = sinon.mock(fakeSocket);

  beforeEach(() => {
    canvasObj = new Canvas(mock);
  });

  describe("disconnect", () => {
    it("calls the appropriate functions", () => {
      mock.expects("end").once();
      mock.expects("destroy").once();
      canvasObj.disconnect();
      mock.verify();
      expect(fakeSocket.end).toHaveBeenCalled();
      expect(fakeSocket.destroy).toHaveBeenCalled();
    });
  });
});

不幸的是，当我运行测试时，它显示 TypeError: this.socket.end is not a function。我有什么遗漏吗？

Answer 1

当我看到您的示例时，我能想到的可能的断开测试脚本有 2 个版本：

1. 使用 sinon.fake()，

// File: canvas.spec.js
const expect = require('expect');
const sinon = require('sinon');
const Canvas = require('./canvas');

describe('Canvas using sinon.fake()', () => {
  const fakeSocket = {
    end: sinon.fake(),
    destroy: sinon.fake(),
    write: sinon.fake(),
  };

  let canvasObj;

  beforeEach(() => {
    canvasObj = new Canvas(fakeSocket);
  });

  describe('disconnect', () => {
    it('calls the appropriate functions', () => {
      canvasObj.disconnect();
      // Note: You can not directly use toHaveBeenCalled() because this is from jest expect, not sinon.
      expect(fakeSocket.end.calledOnce).toBe(true);
      expect(fakeSocket.destroy.calledOnce).toBe(true);
    });
  });
});

1. 使用 sinon.mock()

// File: canvas2.spec.js
const expect = require('expect');
const sinon = require('sinon');
const net = require('net');
const Canvas = require('./canvas');

describe('Canvas using sinon.mock()', () => {
  let canvasObj;
  const socket = new net.Socket();
  const mock = sinon.mock(socket);
  
  beforeEach(() => {
    // Note: Subject under test is socket, not mock.
    canvasObj = new Canvas(socket);
  });

  describe('disconnect', () => {
    it('calls the appropriate functions', () => {
      mock.expects('end').once();
      mock.expects('destroy').once();
      canvasObj.disconnect();
      mock.verify();
    });
  });
});

当我从终端使用 mocha 运行它时：

$ npx mocha *.spec.js


  Canvas using sinon.mock()
    disconnect
      ✔ calls the appropriate functions

  Canvas using sinon.fake()
    disconnect
      ✔ calls the appropriate functions


  2 passing (16ms)

补充说明：fake function / spy 被调用一次的 sinon 期望是：calledOnce 而不是 toHaveBeenCalled()。