NodeJS:aws-sdk 的模拟承诺

Question

我目前正在NodeJS中处理一些代码。

我的代码如下所示：

const AWS = require('aws-sdk');
const PARAMS_ACCOUNT = {
  AttributeNames: [
     "max-instances"
  ]
 };
const ec2 = new AWS.EC2();
const getAccountAttributes = ec2.describeAccountAttributes(PARAMS_ACCOUNT).promise();
function maxInstances() {
    return getAccountAttributes.then(data => {
        return  data.AccountAttributes[0].AttributeValues[0].AttributeValue;
    });
 }

我尝试使用aws-sdk-mock，除了chaiJS和mochaJS，但我不确定如何嘲笑aws-sdk的.promise()。

我的尝试如下所示：

const chai = require('chai');
const mocha = require('mocha');
const awsSDK = require('aws-sdk');
const aws = require('aws-sdk-mock');
const server = require('../instance_limit.js');
const expect = chai.expect;
describe('Sample test', () => {
 it('this is also a test', () => {
  aws.mock('EC2','describeAccountAttributes',function (params, callback){
    callback(null, {AccountAttributes:[{AttributeValues:[{AttributeValue: 10}]}]});
  });
  var awsEC2 = new awsSDK.EC2();
   const instances = server.maxInstances();
   expect(instances).to.equal(10);
  });
});

但是有了这个，我无法嘲笑aws-sdk电话。感谢您的帮助。

Answer 1

我能够通过使用依赖注入原理来解决问题，该原则可以防止在这种情况下模拟 aws 开发工具包，因为有必要稍微调整我的函数并设置默认值。它现在看起来像这样：

const AWS = require('aws-sdk');
const PARAMS_ACCOUNT = {
  AttributeNames: [
 "max-instances"
  ]
 };
const ec2 = new AWS.EC2();
const getAccountAttributes = ec2.describeAccountAttributes(PARAMS_ACCOUNT).promise();
function maxInstances(accountAttributes = getAccountAttributes()) {
    return accountAttributes.then(data => {
        return data.AccountAttributes[0].AttributeValues[0].AttributeValue;
    });
}

现在，这允许我在测试期间提供一个示例值，如下所示：

const chai = require('chai');
const mocha = require('mocha');
const server = require('../instance_limit.js');
const expect = chai.expect;
describe('data calculation based on ec2 values', () => {
 it(' expects to return max Instances value equal 10', () => {
   const accountAttributeObject = {AccountAttributes:[{AttributeValues:[{AttributeValue: 10}]}]}
   const accountAttributes = Promise.resolve(accountAttributeObject);
   const instances = server.maxInstances(accountAttributes);
   return instances.then( data => {
     expect(data).to.equal(10);
   });
  });
})