@revoloo/cypress6/packages/net-stubbing/lib/server/intercept-response.ts

Cypress.io end to end testing tool

import _ from 'lodash'
import { concatStream, httpUtils } from '@packages/network'
import Debug from 'debug'
import { Readable, PassThrough } from 'stream'

import {
  ResponseMiddleware,
} from '@packages/proxy'
import {
  NetStubbingState,
} from './types'
import {
  CyHttpMessages,
  NetEventFrames,
  SERIALIZABLE_RES_PROPS,
} from '../types'
import {
  emit,
  sendStaticResponse,
  setResponseFromFixture,
  getBodyStream,
} from './util'

const debug = Debug('cypress:net-stubbing:server:intercept-response')

export const InterceptResponse: ResponseMiddleware = function () {
  const backendRequest = this.netStubbingState.requests[this.req.requestId]

  debug('InterceptResponse %o', { req: _.pick(this.req, 'url'), backendRequest })

  if (!backendRequest) {
    // original request was not intercepted, nothing to do
    return this.next()
  }

  backendRequest.incomingRes = this.incomingRes

  backendRequest.onResponse = (incomingRes, resStream) => {
    this.incomingRes = incomingRes

    backendRequest.continueResponse!(resStream)
  }

  backendRequest.continueResponse = (newResStream?: Readable) => {
    if (newResStream) {
      this.incomingResStream = newResStream.on('error', this.onError)
    }

    this.next()
  }

  const frame: NetEventFrames.HttpResponseReceived = {
    routeHandlerId: backendRequest.route.handlerId!,
    requestId: backendRequest.requestId,
    res: _.extend(_.pick(this.incomingRes, SERIALIZABLE_RES_PROPS), {
      url: this.req.proxiedUrl,
    }) as CyHttpMessages.IncomingResponse,
  }

  const res = frame.res as CyHttpMessages.IncomingResponse

  const emitReceived = () => {
    emit(this.socket, 'http:response:received', frame)
  }

  this.makeResStreamPlainText()

  new Promise((resolve) => {
    if (httpUtils.responseMustHaveEmptyBody(this.req, this.incomingRes)) {
      resolve('')
    } else {
      this.incomingResStream.pipe(concatStream((resBody) => {
        resolve(resBody)
      }))
    }
  })
  .then((body) => {
    const pt = this.incomingResStream = new PassThrough()

    pt.end(body)

    res.body = String(body)
    emitReceived()

    if (!backendRequest.waitForResponseContinue) {
      this.next()
    }

    // this may get set back to `true` by another route
    backendRequest.waitForResponseContinue = false
  })
}

export async function onResponseContinue (state: NetStubbingState, frame: NetEventFrames.HttpResponseContinue) {
  const backendRequest = state.requests[frame.requestId]

  if (typeof backendRequest === 'undefined') {
    return
  }

  const { res } = backendRequest

  debug('_onResponseContinue %o', { backendRequest: _.omit(backendRequest, 'res.body'), frame: _.omit(frame, 'res.body') })

  const throttleKbps = _.get(frame, 'staticResponse.throttleKbps') || frame.throttleKbps
  const delay = _.get(frame, 'staticResponse.delay') || frame.delay

  if (frame.staticResponse) {
    // replacing response with a staticResponse
    await setResponseFromFixture(backendRequest.route.getFixture, frame.staticResponse)

    const staticResponse = _.chain(frame.staticResponse).clone().assign({ delay, throttleKbps }).value()

    return sendStaticResponse(backendRequest, staticResponse)
  }

  // merge the changed response attributes with our response and continue
  _.assign(res, _.pick(frame.res, SERIALIZABLE_RES_PROPS))

  const bodyStream = getBodyStream(res.body, { throttleKbps, delay })

  return backendRequest.continueResponse!(bodyStream)
}