Simplifying the struggle of mocking and reimplementing NextAPIRequests and NextAPIResponses in order to test and validate NextJS serverless functions.

Installation

Choose your favorite package manager to install the next-testing library

NPM

npm install --save-dev @next-testing/api

Yarn

yarn add -D @next-testing/api

PNPM

pnpm add -D @next-testing/api

Usage

Mocking Simple `GET` Request

import ServerlessFunctionApi from './pages/api/v1/myApi'
import { NextApiRequestBuilder, ResponseMock } from '@next-testing/api'

test("Get Request and Response Mock", () => {
  const req = new NextApiRequestBuilder().setMethod('GET').build()
  const res = ResponseMock<MyResult>()

  ServerlessFunctionApi(req, res)

  expect(res.getStatusCode()).toEqual(405)
  expect(res.getBodyJson()).toStrictEqual({
      success: false,
      message: 'Method not allowed',
  })
})

Mocking Simple `POST` Request

import ServerlessFunctionApi from './pages/api/v1/myApi'
import { NextApiRequestBuilder, ResponseMock } from '@next-testing/api'

it('Post Request and Response Mock', async () => {
    const req = new NextApiRequestBuilder().setMethod('POST').build()
    const res = ResponseMock<MyResult>()

    ServerlessFunctionApi(req, res)

    expect(res.getStatusCode()).toEqual(401)
    expect(res.getBodyJson()).toStrictEqual({
        success: false,
        message: 'access denied',
    })
})

Mocking Request with Headers

import ServerlessFunctionApi from './pages/api/v1/myApi'
import { NextApiRequestBuilder, ResponseMock } from '@next-testing/api'

it('Mock Request and Response with headers', async () => {
  const req = new NextApiRequestBuilder()
          .setMethod('POST')
          .setHeaders({ authorization: 'Bearer ABC123' })
          .build()
  const res = ResponseMock<CronResult>()

  ServerlessFunctionApi(req, res)

  expect(res.getStatusCode()).toEqual(401)
  expect(res.getBodyJson()).toStrictEqual({
      success: false,
      message: 'access denied',
  })
})

Mocking Request with Headers, Body & Cookies

import ServerlessFunctionApi from './pages/api/v1/myApi'
import { NextApiRequestBuilder, ResponseMock } from '@next-testing/api'

it('Mock Request and Response with headers', async () => {
  const req = new NextApiRequestBuilder()
          .setMethod('POST')
          .setHeaders({ authorization: 'Bearer ABC123' })
          .setCookies({ apiKey: "mytoken" })
          .setBody({
              posts: [{
                  content: "hello world"
              }]
          })
          .build()
  const res = ResponseMock<CronResult>()

  ServerlessFunctionApi(req, res)

  expect(res.getStatusCode()).toEqual(401)
  expect(res.getBodyJson()).toStrictEqual({
      success: false,
      message: 'access denied',
  })
})

Mocking Request with route parameters

If your handler depends on some parameters found in the path, eg. it's defined in pages/api/[foo]/echo, then you can specify it with setQuery().

import EchoHandler from './pages/api/[foo]/echo'
import { NextApiRequestBuilder, ResponseMock } from '@next-testing/api'

it('Mock Request and Response with route parameters', async () => {
  const req = new NextApiRequestBuilder()
          .setMethod('GET')
          .setQuery({
            foo: 'hello'
          })
          .build()
  const res = ResponseMock()

  EchoHandler(req, res)

  expect(res.getStatusCode()).toEqual(200)
  expect(res.getBodyJson()).toStrictEqual({
      foo: 'hello',
  })
})

marpme/next-testing-api