如何在測試下一頁 api 時開玩笑地模擬 mongodb 客戶端？

Question

我想用玩笑測試下一頁 api 文件，雖然目前測試運行良好，但我遇到了一些問題

1. 每個頁面 API 發出的 POST 請求實際上都是在向 mongo 數據庫發送數據，即使我正在運行測試； 這是不可取的，因為當我測試此類 POST 請求時，我不希望測試數據在數據庫中
2. 在某些情況下，我想模擬 mongo 連接失敗，以測試 500 狀態錯誤響應，但我不知道該怎么做

如何模擬 mongoclient 連接，以便在連接成功后測試將項目插入數據庫，或者故意導致 mongo 客戶端連接錯誤？

    newsletter.ts (PAGE API FILE)
    import type { NextApiRequest, NextApiResponse } from 'next'
import { MongoClient } from 'mongodb'

async function connectDatabase() {
  const client = await MongoClient.connect(<url>)
  return client
}

async function insertDocument(client: MongoClient, document: { email: string }) {
  const db = client.db()
  await db.collection('newsletter').insertOne(document)
}

async function handler(req: NextApiRequest, res: NextApiResponse) {
  const userEmail = JSON.parse(req.body).email
  if (!userEmail || !userEmail.includes('@')) {
    res.status(422).json({ message: 'Invalid email address' })
    return
  }

  let client
  try {
    client = await connectDatabase()

  } catch (error) {
    res.status(500).json({ message: 'Connecting to the database failed!' })
    return
  }

  try {
    await insertDocument(client, { email: userEmail })

  } catch(error) {
    res.status(500).json({ message: 'Inserting data failed!' })
    return
  }

  client.close()

  res.status(201).json({ message: 'Signed up!' })

}

export default handler

這是測試代碼

newsletter.test.tsx (PAGE API TEST FILE)

import type { NextApiRequest, NextApiResponse } from 'next'
import {
  createMocks as _createMocks,
  Mocks,
  RequestOptions,
  ResponseOptions,
} from 'node-mocks-http'

import newsletter from '../../pages/api/newsletter'



const createMocks = _createMocks as (
  reqOptions?: RequestOptions,
  resOptions?: ResponseOptions

) => Mocks<NextApiRequest, NextApiResponse>

describe('Test responses for newsletter api', () => {
  it('Should return status 201 with valid request body', async () => {
    const { req, res } = createMocks({
      method: 'POST',
      body: JSON.stringify({
        email: 'abc@email.com',
      }),
    })
    await newsletter(req, res)
    expect(res._getStatusCode()).toBe(201)
    expect(JSON.parse(res._getData())) .toEqual(
      expect.objectContaining({
        message: 'Signed up!',
      })
    )
  })

  it('Should return status 422 with invalid req body', async () => {
    const { req, res } = createMocks({
      method: 'POST',
      body: JSON.stringify({
        email: 'abcemail.com',
      }),
    })
    await newsletter(req, res)
    expect(res._getStatusCode()).toBe(422)
    expect(JSON.parse(res._getData())).toEqual(
      expect.objectContaining({
        message: 'Invalid email address',
      })
    )
  })
})

Answer 1

找到了幫助我解決問題的答案

為了模擬 mongoclient，我只需要使用 jest.spyOn，並將用戶的所有其他函數鏈接到數據庫中。 這也阻止了對服務器的真正調用，並且不再發送測試數據。 為了模擬狀態 500 錯誤，我只是模擬了一個被拒絕的 promise。

代碼最終變成了這樣：

import type { NextApiRequest, NextApiResponse } from 'next'
import {
  createMocks as _createMocks,
  Mocks,
  RequestOptions,
  ResponseOptions,
} from 'node-mocks-http'
import { MongoClient } from 'mongodb'

import newsletter from '../../pages/api/newsletter'



const createMocks = _createMocks as (
  reqOptions?: RequestOptions,
  resOptions?: ResponseOptions
) => Mocks<NextApiRequest, NextApiResponse>
describe('Test responses for newsletter api', () => {

  afterEach(() => {
    jest.resetAllMocks()
  })

  it('Should return status 500 on failure to connect to database', async () => {
    const { req, res } = createMocks({
      method: 'POST',
      //@ts-ignore
      body: JSON.stringify({
        email: 'abc@email.com',
      }),
    })
    const connectSpy = jest.spyOn(MongoClient, 'connect').mockRejectedValueOnce(new Error)
    await newsletter(req, res)
    expect(connectSpy).toHaveBeenCalled()
    expect(res._getStatusCode()).toBe(500)
  })


  it('Should return status 201 with valid request body', async () => {
    const { req, res } = createMocks({
      method: 'POST',
      //@ts-ignore
      body: JSON.stringify({
        email: 'abc@email.com',
      }),
    })
    const insertOne = jest.fn().mockResolvedValueOnce({ acknowleged: true })
    const collection = jest.fn().mockReturnValueOnce({ insertOne })
    const connectSpy = jest.spyOn(MongoClient, 'connect').mockResolvedValueOnce({ db: jest.fn().mockReturnValueOnce({ collection }), close: jest.fn() })
    await newsletter(req, res)
    expect(connectSpy).toHaveBeenCalled()
    expect(res._getStatusCode()).toBe(201)
    expect(JSON.parse(res._getData())) .toEqual(
      expect.objectContaining({
        message: 'Signed up!',
      })
    )
  })

})