Firebase test helper as a set up util for npm lib 'firebase-server'.

firebase-faker.js

import proxyquire from 'proxyquire'
import originalWebsocket from 'faye-websocket'
import FirebaseServer from 'firebase-server'

const localhostWS = {
  'faye-websocket': {
    '@global': true,
    Client: url => {
      const localhostUrl = url.replace(/dummy\d+\.firebaseio\.test/i, 'localhost')
      return new originalWebsocket.Client(localhostUrl)
    }
  }
}

// Firebase has strict requirements about the hostname format. So we provide a dummy
// hostname and then change the URL to localhost inside the faye-websocket's Client
// constructor.
const firebase = proxyquire('firebase', localhostWS)

// Turn this on if you want to see the useless Firebase logs
firebase.database.enableLogging(false)

let sequentialConnectionId = 0

// Fake Firebase apps are identified by port numbers,
// i.e. use different port numbers when you want to support multiple apps.
export function newFirebaseClient(port, authToken) {
  const name = 'test-firebase-client-' + sequentialConnectionId
  const url = 'ws://dummy' + (sequentialConnectionId++) + '.firebaseio.test:' + port
  const config = {
    databaseURL: url,
    serviceAccount: {
      'private_key': 'fake',
      'client_email': 'fake'
    }
  }
  overwriteAuth(authToken)
  const app = firebase.initializeApp(config, name)
  return app.database()
}


// Override Firebase client authentication mechanism. This allows us to set custom auth tokens during
// tests, as well as authenticate anonymously.
function overwriteAuth(token) {
  firebase.INTERNAL.factories.auth = (app, extendApp) => {
    const _listeners = []
    extendApp({
      'INTERNAL': {
        'getToken': () => {
          if (!token) {
            return Promise.resolve(null)
          }
          _listeners.forEach(listener => {
            listener(token)
          })
          return Promise.resolve({ accessToken: token, expirationTime: 1566618502074 })
        },
        'addAuthTokenListener': listener => {
          _listeners.push(listener)
        }
      }
    })
  }
}

export function setupDatabase(port, data, authToken) {
  const server = new FirebaseServer(port, 'localhost:' + port, data)
  const client = newFirebaseClient(port, authToken)
  return { server, client }
}

export function destroyDatabase(server, client) {
  client.goOffline()
  server.close()
  server = null
}