Vercel Emulate：LocalStack代替の軽量マルチサービスエミュレーターでAWS/外部APIテストを自動化

import { createEmulator } from 'emulate'

const github = await createEmulator({ service: 'github', port: 4001 })
const vercel = await createEmulator({ service: 'vercel', port: 4002 })

github.url   // 'http://localhost:4001'
vercel.url   // 'http://localhost:4002'

await github.close()
await vercel.close()

// vitest.setup.ts
import { createEmulator, type Emulator } from 'emulate'

let github: Emulator
let vercel: Emulator

beforeAll(async () => {
  ;[github, vercel] = await Promise.all([
    createEmulator({ service: 'github', port: 4001 }),
    createEmulator({ service: 'vercel', port: 4002 })
  ])
})

afterAll(async () => {
  await Promise.all([github.close(), vercel.close()])
})

import { createEmulator } from 'emulate'
import { SQSClient, SendMessageCommand, ReceiveMessageCommand } from '@aws-sdk/client-sqs'

const aws = await createEmulator({ service: 'aws', port: 4006 })

const sqs = new SQSClient({
  region: 'us-east-1',
  endpoint: aws.url,
  credentials: { accessKeyId: 'test', secretAccessKey: 'test' }
})

const queueUrl = `${aws.url}/000000000000/test-queue`

// メッセージ送信
await sqs.send(new SendMessageCommand({
  QueueUrl: queueUrl,
  MessageBody: JSON.stringify({ event: 'user.created', userId: '123' })
}))

// メッセージ受信
const { Messages } = await sqs.send(new ReceiveMessageCommand({
  QueueUrl: queueUrl,
  MaxNumberOfMessages: 10
}))
console.log(Messages)

await aws.close()

import { createEmulator } from 'emulate'
import { S3Client, PutObjectCommand, GetObjectCommand } from '@aws-sdk/client-s3'

const aws = await createEmulator({ service: 'aws', port: 4006 })

const s3 = new S3Client({
  region: 'us-east-1',
  endpoint: aws.url,
  forcePathStyle: true, // ローカルエミュレーターでは必須
  credentials: { accessKeyId: 'test', secretAccessKey: 'test' }
})

// ファイルアップロード
await s3.send(new PutObjectCommand({
  Bucket: 'test-bucket',
  Key: 'uploads/report.json',
  Body: JSON.stringify({ result: 'ok' }),
  ContentType: 'application/json'
}))

// ファイル取得
const { Body } = await s3.send(new GetObjectCommand({
  Bucket: 'test-bucket',
  Key: 'uploads/report.json'
}))
const text = await Body?.transformToString()
console.log(text) // '{"result":"ok"}'

await aws.close()

// s3.test.ts
import { createEmulator, type Emulator } from 'emulate'
import { S3Client, PutObjectCommand, GetObjectCommand } from '@aws-sdk/client-s3'

let aws: Emulator
let s3: S3Client

beforeAll(async () => {
  aws = await createEmulator({ service: 'aws', port: 4006 })
  s3 = new S3Client({
    region: 'us-east-1',
    endpoint: aws.url,
    forcePathStyle: true,
    credentials: { accessKeyId: 'test', secretAccessKey: 'test' }
  })
})

afterAll(() => aws.close())

test('S3にファイルをアップロードして取得できる', async () => {
  await s3.send(new PutObjectCommand({
    Bucket: 'test-bucket',
    Key: 'test.txt',
    Body: 'hello world'
  }))

  const { Body } = await s3.send(new GetObjectCommand({
    Bucket: 'test-bucket',
    Key: 'test.txt'
  }))

  expect(await Body?.transformToString()).toBe('hello world')
})

import { createEmulator } from 'emulate'
import { WebClient } from '@slack/web-api'

const slack = await createEmulator({ service: 'slack', port: 4003 })

// slackApiUrl にエミュレーターURLを指定
const client = new WebClient('xoxb-test-token', {
  slackApiUrl: `${slack.url}/api/`
})

const result = await client.chat.postMessage({
  channel: '#general',
  text: 'デプロイ完了！ :rocket:',
  blocks: [
    {
      type: 'section',
      text: { type: 'mrkdwn', text: '*デプロイ完了*\n本番環境へのデプロイが成功しました。' }
    }
  ]
})

console.log('Message sent, ts:', result.ts)
await slack.close()

import { createEmulator } from 'emulate'
import { IncomingWebhook } from '@slack/webhook'

const slack = await createEmulator({ service: 'slack', port: 4003 })

// WebhookのURLをエミュレーターに向ける
const webhook = new IncomingWebhook(
  `${slack.url}/services/T00000000/B00000000/XXXXXXXXXX`
)

await webhook.send({
  text: 'CI/CDパイプラインが完了しました',
  attachments: [
    {
      color: 'good',
      fields: [
        { title: 'ブランチ', value: 'main', short: true },
        { title: 'ステータス', value: '成功', short: true }
      ]
    }
  ]
})

await slack.close()

import { createEmulator, type Emulator } from 'emulate'

let slackEmulator: Emulator

beforeAll(async () => {
  slackEmulator = await createEmulator({ service: 'slack', port: 4003 })
})

afterAll(() => slackEmulator.close())

test('slash commandに正しく応答する', async () => {
  // エミュレーターにslash commandリクエストを直接送信
  const response = await fetch(`${slackEmulator.url}/commands`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
    body: new URLSearchParams({
      command: '/deploy',
      text: 'production',
      user_id: 'U123456',
      channel_id: 'C123456'
    })
  })
  expect(response.ok).toBe(true)
})

import { createEmulator, type Emulator } from 'emulate'
import { SQSClient, SendMessageCommand } from '@aws-sdk/client-sqs'
import { WebClient } from '@slack/web-api'

let aws: Emulator
let slack: Emulator

beforeAll(async () => {
  ;[aws, slack] = await Promise.all([
    createEmulator({ service: 'aws', port: 4006 }),
    createEmulator({ service: 'slack', port: 4003 })
  ])
})

afterAll(async () => {
  await Promise.all([aws.close(), slack.close()])
})

test('SQSメッセージ受信後にSlack通知を送る', async () => {
  const sqs = new SQSClient({
    region: 'us-east-1',
    endpoint: aws.url,
    credentials: { accessKeyId: 'test', secretAccessKey: 'test' }
  })
  const slackClient = new WebClient('xoxb-test-token', {
    slackApiUrl: `${slack.url}/api/`
  })

  // SQSにイベントを投入
  await sqs.send(new SendMessageCommand({
    QueueUrl: `${aws.url}/000000000000/events`,
    MessageBody: JSON.stringify({ type: 'order.completed', orderId: '456' })
  }))

  // Slack通知関数を呼び出してテスト
  const result = await slackClient.chat.postMessage({
    channel: '#orders',
    text: '注文 #456 が完了しました'
  })

  expect(result.ok).toBe(true)
})