开玩笑模拟 Knex 交易

Question

我有以下 lambda 处理程序来进行单元测试。它使用一个库@org/aws-connection，它有一个函数mysql.getIamConnection，它只返回一个knex连接。

编辑：我在帖子底部添加了mysql.getIamConnection 函数

编辑：如果可能的话，我想只用 Jest 进行测试。那是除非它变得复杂

index.js

const {mysql} = require('@org/aws-connection');

exports.handler = async (event) => {
  const connection = await mysql.getIamConnection()

  let response = {
    statusCode: 200,
    body: {
      message: 'Successful'
    }
  }

  try {
    for(const currentMessage of event.Records){
      let records = JSON.parse(currentMessage.body);
      
      await connection.transaction(async (trx) => {
        await trx
            .table('my_table')
            .insert(records)
            .then(() =>
                console.log(`Records inserted into table ${table}`))
            .catch((err) => {
                console.log(err)
                throw err
            })
      })
    }
  } catch (e) {
    console.error('There was an error while processing', { errorMessage: e})

    response = {
      statusCode: 400,
      body: e
    }
  } finally {
    connection.destroy()
  }
  return response
}

我已经编写了一些单元测试，并且能够模拟 connection.transaction 函数，但我在使用 trx.select.insert.then.catch 函数时遇到了问题。 H

这是我的测试文件 index.test.js

import { handler } from '../src';
const mocks = require('./mocks');

jest.mock('@org/aws-connection', () => ({
    mysql: {
        getIamConnection: jest.fn(() => ({
            transaction: jest.fn(() => ({
                table: jest.fn().mockReturnThis(),
                insert: jest.fn().mockReturnThis()
            })),
            table: jest.fn().mockReturnThis(),
            insert: jest.fn().mockReturnThis(),
            destroy: jest.fn().mockReturnThis()
        }))
    }
}))

describe('handler', () => {
    test('test handler', async () =>{
      const response = await handler(mocks.eventSqs)
      expect(response.statusCode).toEqual(200)
    });
});

此测试部分有效，但根本不涵盖trx 部分。这些线没有被发现

await trx
        .table('my_table')
        .insert(records)
        .then(() =>
            console.log(`Records inserted into table ${table}`))
        .catch((err) => {
            console.log(err)
            throw err
        })

如何设置我的模拟 @org/aws-connection 使其也涵盖 trx 功能？

编辑： mysql.getIamConnection

async function getIamConnection (secretId, dbname) {
    const secret = await getSecret(secretId)

    const token = await getToken(secret)

    let knex
    console.log(`Initialzing a connection to ${secret.proxyendpoint}:${secret.port}/${dbname} as ${secret.username}`)
    knex = require('knex')(
        {
            client: 'mysql2',
            connection: {
                host: secret.proxyendpoint,
                user: secret.username,
                database: dbname,
                port: secret.port,
                ssl: 'Amazon RDS',
                authPlugins: {
                    mysql_clear_password: () => () => Buffer.from(token + '\0')
                },
                connectionLimit: 1
            }
        }
    )

    return knex
}

解决方案

@qaismakani 的回答对我有用。我写的略有不同，但回调是关键。对于任何对此感兴趣的人，这是我的最终解决方案

const mockTrx = {
    table: jest.fn().mockReturnThis(),
    insert: jest.fn().mockResolvedValue()
}

jest.mock('@org/aws-connection', () => ({
    mysql: {
        getIamConnection: jest.fn(() => ({
            transaction: jest.fn((callback) => callback(mockTrx)),
            destroy: jest.fn().mockReturnThis()
        }))
    }
}))

Answer 1

好的，让我们看看。更新你的模拟看起来像这样可能会奏效：

const {mysql} = require('@org/aws-connection');
jest.mock('@org/aws-connection', () => ({
    mySql: {
        getIamConnection: jest.fn()
    }
}));


const mockTrx = {
  table: jest.fn().mockReturnThis(),
  insert: jest.fn().mockResolveValue() // resolve any data here
};
mysql.getIamConnection.mockReturnValue({
    transaction: jest.fn((callback) => callback(mockTrx)),
});

编辑：解释

您需要以一种使用虚拟 trx 调用回调的方式模拟事务。现在要正确获取虚拟 trx，您需要确保虚拟 trx 对象中的所有函数都返回对它的引用或承诺，以便您可以适当地链接它。

Answer 2

我没有模拟 knex 实现，而是编写了 knex-mock-client，它允许您使用简单的 API 模拟真实的数据库。

改变你的模拟实现

import { handler } from "../src";
import { getTracker } from "knex-mock-client";
const mocks = require("./mocks");

jest.mock("@org/aws-connection", () => {
  const knex = require("knex");
  const { MockClient } = require("knex-mock-client");
  return {
    mysql: {
      getIamConnection: () => knex({ client: MockClient }),
    },
  };
});

describe("handler", () => {
  test("test handler", async () => {
    const tracker = getTracker();
    tracker.on.insert("my_table").responseOnce([23]); // setup's a mock response when inserting into my_table

    const response = await handler(mocks.eventSqs);
    expect(response.statusCode).toEqual(200);
  });
});