e2e.ts

import { create } from 'axios'
import { type AxiosTestInstance, patchInstance } from 'axios-test-instance'
import { json } from 'body-parser'
import * as express from 'express'

// ——— Shared types ———

interface Credentials {
  /**
   * The password the user entered.
   */
  password: string

  /**
   * The username the user entered.
   */
  username: string
}

interface TokenResponse {
  /**
   * An OAuth2 access token.
   */
  access_token: string
}

// ——— Backend ———

const users: Credentials[] = [
  {
    password: 'I love krabby patties!',
    username: 'spongebob'
  }
]

const backend = express()
backend.use(json())
backend.post<never, TokenResponse, Credentials>('/api/token', (req, res) => {
  const { password, username } = req.body
  const user = users.find((u) => u.username === username && u.password === password)
  if (user) {
    res.json({ access_token: 'super.secret.token' })
  } else {
    res.status(401)
  }
})

// ——— Frontend ———

const request = create({ baseURL: '/api' })

/**
 * Authorize the client side default axios instance.
 *
 * @param credentials The credentials to login with.
 */
async function login(credentials: Credentials): Promise<void> {
  const { data } = await request.post<TokenResponse>('/token', credentials)
  request.defaults.headers.common.Authorization = `Bearer ${data.access_token}`
}

// ——— Test ———

let instance: AxiosTestInstance

beforeAll(async () => {
  instance = await patchInstance(request, backend)
})

afterAll(async () => {
  await instance.close()
})

it('should be possible to login', async () => {
  await login({
    password: 'I love krabby patties!',
    username: 'spongebob'
  })
  expect(request.defaults.headers.common.Authorization).toBe('Bearer super.secret.token')
})