Sinon如何在mysql2.createPool函数中对双箭头函数进行单元测试答案

【问题标题】：Sinon how to unit test double arrow function within mysql2.createPool functionSinon如何在mysql2.createPool函数中对双箭头函数进行单元测试
【发布时间】：2020-10-11 03:57:07
【问题描述】：

我有一个 Connection 类，用于连接到 AWS RDS Aurora 数据库实例。该类工作正常，但我无法获得完整的单元测试覆盖率。有一件我不知道如何覆盖。它是mysql_clear_password: () => () => Buffer.from(this.options.password + '\0')，显示在下面的 Connection 类中。我怎样才能覆盖那条特定的线？是否需要重构函数？

我已尝试将 Buffer 函数移至单独的函数，但覆盖率报告仍显示原始行未被覆盖

连接类：

const mysql2 = require('mysql2/promise');

class Connection {
    constructor(options = {}) {
        this.options = options;
    }

    createPool () {
        this.pool = mysql2.createPool({
            host: this.options.host,
            user: this.options.user,
            database:  'my_db',
            ssl: 'Amazon RDS',
            password: this.options.password,
            authPlugins: {
                mysql_clear_password: () => () => Buffer.from(this.options.password + '\0')
            }
        });
    }
}
module.exports = { Connection };

这是我目前的测试结果：

const conns = require('../src/connection');
const sinon = require('sinon');
const mysql2 = require('mysql2/promise');

    describe('connection', () => {
         afterEach(() => {
           sinon.restore();
        });
    
        test('Test creatPool function from connection class', async () => {
            const options = {
                host: 'testHost',
                user: 'testUser',
                password: 'testPassword'
            };
    
            const createPoolStub = sinon.stub(mysql2, 'createPool').returns(sinon.stub().returnsThis());
            const conn = new conns.Connection(options);
            await conn.createPool();
            sinon.assert.calledOnce(createPoolStub);
        });
    });

【问题讨论】：

标签： node.js unit-testing aws-lambda amazon-rds sinon

【解决方案1】：

使用stub.callsFake 方法使存根(mysql2.createPool) 在调用时调用提供的函数。然后，您可以从测试用例中提供的函数中获取mysql_clear_password 方法。

例如

connection.js:

const mysql2 = require('mysql2/promise');

class Connection {
  constructor(options = {}) {
    this.options = options;
  }

  createPool() {
    this.pool = mysql2.createPool({
      host: this.options.host,
      user: this.options.user,
      database: 'my_db',
      ssl: 'Amazon RDS',
      password: this.options.password,
      authPlugins: {
        mysql_clear_password: () => () => Buffer.from(this.options.password + '\0'),
      },
    });
  }
}
module.exports = { Connection };

connection.test.js:

const mysql2 = require('mysql2/promise');
const conns = require('./connection');
const sinon = require('sinon');
const { expect } = require('chai');

describe('64300458', () => {
  it('Test creatPool function from connection class', () => {
    const options = {
      host: 'testHost',
      user: 'testUser',
      password: 'testPassword',
    };

    let configRef;
    const createPoolStub = sinon.stub(mysql2, 'createPool').callsFake((config) => {
      configRef = config;
    });

    const conn = new conns.Connection(options);
    conn.createPool();
    sinon.assert.calledOnce(createPoolStub);

    // test mysql_clear_password
    const actual = configRef.authPlugins.mysql_clear_password()();
    expect(actual).to.be.eql(Buffer.from('testPassword\0'));
    createPoolStub.restore();
  });
});

带有覆盖率报告的单元测试结果：

  64300458
    ✓ Test creatPool function from connection class


  1 passing (11ms)

---------------|---------|----------|---------|---------|-------------------
File           | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
---------------|---------|----------|---------|---------|-------------------
All files      |     100 |        0 |     100 |     100 |                   
 connection.js |     100 |        0 |     100 |     100 | 4                 
---------------|---------|----------|---------|---------|-------------------

【讨论】：