无法正确模拟承诺和回调

Question

我正在尝试在 js 文件 'eslModule.js' 中测试以下方法，但没有成功

async function exec(cmd, args, ip, port) {
    const connPromise = new Promise(function(resolve, reject) {

        try {
            sock = new esl.Connection(ip, port, 'pwd', function() {
                sock.bgapi(command, function(result) {
                    if (sock && sock.socket.writable && sock.socket.readable) {
                        sock.disconnect();
                    }
                    return resolve({
                        result: result.body
                    });
                });
            });
        } catch (error) {
            return reject(error);
        }

        sock.on('error', function(error) {

            if (sock === null) {
                return false;
            }
            if (error.code === 'ERR1' || error.code === 'ERR2') {
                error.message = `Connection failed: [${error.code}]`;
            }
            if (sock && sock.socket.writable && sock.socket.readable) {
                sock.disconnect();
            }

            return reject(error);
        });

        try {
            await connPromise;
        } catch (error) {
            sock = null;
            throw error;
        }
    });
}

这就是测试的样子

const esl = require('modesl');
const eslModule = rewire(`<PATH TO MODULE>`);
(...)

it('It should return a valid response', async function () {
        
    const cmd = "c";
    const args = "t";
    const ip = "127.0.0.1";
    const port = '<port>'

    const expResp = {
        result: '+OK---- 00000000-0000-0000-0000-000000000000'
     }

    stub1 = sinon.stub(esl, 'Connection').yields(ip, port, 'pwd',expResp);

    const result = await eslModule.exec(cmd, args, ip, port);
    expect(result).resolves.to.deep.equal(expResp);
    sinon.assert.calledOnce(stub1);
});

但我没有让它工作，因为测试进入了 Promise，然后在 sock.bgapi 回复无法访问未定义的 bgapi...

如果我尝试模拟错误（在 sock.on('error' ...) 中，我会得到类似的回复，即 .on 不是方法。

Answer 1

你需要伪造 bgapi 和 on 方法。

这只是一个例子：我根据你的代码创建文件 eslModule.js。

// File eslModule.js
const esl = require('modesl');

async function exec(cmd, args, ip, port) {
  return new Promise(function(resolve, reject) {
    try {
      sock = new esl.Connection(ip, port, 'pwd', function() {
        sock.bgapi(cmd, function(result) {
          if (sock && sock.socket.writable && sock.socket.readable) {
            sock.disconnect();
          }
          return resolve({
            result: result.body
          });
        });
      });
    } catch (error) {
      return reject(error);
    }

    sock.on('error', function(error) {
      if (sock === null) {
        return false;
      }
      if (error.code === 'ERR1' || error.code === 'ERR2') {
        error.message = `Connection failed: [${error.code}]`;
      }
      if (sock && sock.socket.writable && sock.socket.readable) {
        sock.disconnect();
      }
      return reject(error);
    });
  });
}

module.exports.exec = exec;

然后是spec文件：eslModule.spec.js

// File: eslModule.spec.js
const esl = require('modesl');
const sinon = require('sinon');
const chai = require('chai');
const chaiAsPromised = require('chai-as-promised');
const eslModule = require('./eslModule');

chai.use(chaiAsPromised);
const { expect } = chai;

it('It should return a valid response', function () {
  const cmd = 'c';
  const args = 't';
  const ip = '127.0.0.1';
  const port = '<port>';
  // Define output.
  const expResp = {
    result: '+OK---- 00000000-0000-0000-0000-000000000000',
  };

  // Prepare variable to store callback function.
  let connectionCallback;
  let bgApiCallback;

  // Create fake sock.
  const sockFake = {
    bgapi: sinon.fake((arg1, arg2) => {
      bgApiCallback = arg2;
    }),
    socket: {
      writable: true,
      readble: true,
    },
    disconnect: sinon.fake(),
    on: sinon.fake(),
  };

  // Create stub on esl.Connection.
  const stubEslConnection = sinon.stub(esl, 'Connection');
  stubEslConnection.callsFake((arg1, arg2, arg3, arg4) => {
    connectionCallback = arg4;
    return sockFake;
  });

  // Call exec function.
  const result = eslModule.exec(cmd, args, ip, port);
  // Make sure all callback function get called.
  connectionCallback();
  bgApiCallback({ body: expResp.result });
  // Result is Promise object, use with eventually.
  expect(result).eventually.to.deep.equal(expResp);
  // Makesure stub get called.
  expect(stubEslConnection.calledOnce).to.equal(true);

  // Do not forget to restore the stub.
  stubEslConnection.restore();
});

当我在终端上使用 mocha 运行它时

$ npx mocha eslModule.spec.js 


  ✓ It should return a valid response

  1 passing (4ms)

注意事项：

• 我从不使用模型模块，我纯粹根据您的代码示例在上面创建测试，
• 我选择使用 chai-as-promised，而不是让它异步运行。
• spec 文件中最棘手的事情是：创建假 sock 对象并处理回调函数。