nock/lib/recorder.js

HTTP server mocking and expectations library for Node.js

'use strict'

const { recorder: debug } = require('./debug')
const querystring = require('querystring')
const { inspect } = require('util')

const common = require('./common')
const { restoreOverriddenClientRequest } = require('./intercept')
const { gzipSync, brotliCompressSync, deflateSync } = require('zlib')
const {
  default: nodeInterceptors,
} = require('@mswjs/interceptors/presets/node')
const SEPARATOR = '\n<<<<<<-- cut here -->>>>>>\n'
let recordingInProgress = false
let outputs = []

// TODO: don't reuse the nodeInterceptors, create new ones.
const clientRequestInterceptor = nodeInterceptors[0]
const fetchRequestInterceptor = nodeInterceptors[2]

function getScope(options) {
  const { proto, host, port } = common.normalizeRequestOptions(options)
  return common.normalizeOrigin(proto, host, port)
}

function getMethod(options) {
  return options.method || 'GET'
}

function getBodyFromChunks(chunks, headers) {
  // If we have headers and there is content-encoding it means that the body
  // shouldn't be merged but instead persisted as an array of hex strings so
  // that the response chunks can be mocked one by one.
  if (headers && common.isContentEncoded(headers)) {
    return {
      body: chunks.map(chunk => chunk.toString('hex')),
    }
  }

  const mergedBuffer = Buffer.concat(chunks)

  // The merged buffer can be one of three things:
  // 1. A UTF-8-representable string buffer which represents a JSON object.
  // 2. A UTF-8-representable buffer which doesn't represent a JSON object.
  // 3. A non-UTF-8-representable buffer which then has to be recorded as a hex string.
  const isUtf8Representable = common.isUtf8Representable(mergedBuffer)
  if (isUtf8Representable) {
    const maybeStringifiedJson = mergedBuffer.toString('utf8')
    try {
      return {
        isUtf8Representable,
        body: JSON.parse(maybeStringifiedJson),
      }
    } catch (err) {
      return {
        isUtf8Representable,
        body: maybeStringifiedJson,
      }
    }
  } else {
    return {
      isUtf8Representable,
      body: mergedBuffer.toString('hex'),
    }
  }
}

function generateRequestAndResponseObject({
  req,
  bodyChunks,
  options,
  res,
  dataChunks,
  reqheaders,
}) {
  const { body, isUtf8Representable } = getBodyFromChunks(
    dataChunks,
    res.headers,
  )
  options.path = req.path

  return {
    scope: getScope(options),
    method: getMethod(options),
    path: options.path,
    // Is it deliberate that `getBodyFromChunks()` is called a second time?
    body: getBodyFromChunks(bodyChunks).body,
    status: res.statusCode,
    response: body,
    rawHeaders: res.rawHeaders,
    reqheaders: reqheaders || undefined,
    // When content-encoding is enabled, isUtf8Representable is `undefined`,
    // so we explicitly check for `false`.
    responseIsBinary: isUtf8Representable === false,
  }
}

function generateRequestAndResponse({
  req,
  bodyChunks,
  options,
  res,
  dataChunks,
  reqheaders,
}) {
  const requestBody = getBodyFromChunks(bodyChunks).body
  const responseBody = getBodyFromChunks(dataChunks, res.headers).body

  // Remove any query params from options.path so they can be added in the query() function
  let { path } = options
  const queryIndex = req.path.indexOf('?')
  let queryObj = {}
  if (queryIndex !== -1) {
    // Remove the query from the path
    path = path.substring(0, queryIndex)

    const queryStr = req.path.slice(queryIndex + 1)
    queryObj = querystring.parse(queryStr)
  }

  // Escape any single quotes in the path as the output uses them
  path = path.replace(/'/g, `\\'`)

  // Always encode the query parameters when recording.
  const encodedQueryObj = {}
  for (const key in queryObj) {
    const formattedPair = common.formatQueryValue(
      key,
      queryObj[key],
      common.percentEncode,
    )
    encodedQueryObj[formattedPair[0]] = formattedPair[1]
  }

  const lines = []

  // We want a leading newline.
  lines.push('')

  const scope = getScope(options)
  lines.push(`nock('${scope}', {"encodedQueryParams":true})`)

  const methodName = getMethod(options).toLowerCase()
  if (requestBody) {
    lines.push(`  .${methodName}('${path}', ${JSON.stringify(requestBody)})`)
  } else {
    lines.push(`  .${methodName}('${path}')`)
  }

  Object.entries(reqheaders || {}).forEach(([fieldName, fieldValue]) => {
    const safeName = JSON.stringify(fieldName)
    const safeValue = JSON.stringify(fieldValue)
    lines.push(`  .matchHeader(${safeName}, ${safeValue})`)
  })

  if (queryIndex !== -1) {
    lines.push(`  .query(${JSON.stringify(encodedQueryObj)})`)
  }

  const statusCode = res.statusCode.toString()
  const stringifiedResponseBody = JSON.stringify(responseBody)
  const headers = inspect(res.rawHeaders)
  lines.push(`  .reply(${statusCode}, ${stringifiedResponseBody}, ${headers});`)

  return lines.join('\n')
}

//  This module variable is used to identify a unique recording ID in order to skip
//  spurious requests that sometimes happen. This problem has been, so far,
//  exclusively detected in nock's unit testing where 'checks if callback is specified'
//  interferes with other tests as its t.end() is invoked without waiting for request
//  to finish (which is the point of the test).
let currentRecordingId = 0

const defaultRecordOptions = {
  dont_print: false,
  enable_reqheaders_recording: false,
  logging: console.log, // eslint-disable-line no-console
  output_objects: false,
  use_separator: true,
}

function record(recOptions) {
  //  Trying to start recording with recording already in progress implies an error
  //  in the recording configuration (double recording makes no sense and used to lead
  //  to duplicates in output)
  if (recordingInProgress) {
    throw new Error('Nock recording already in progress')
  }

  recordingInProgress = true

  // Set the new current recording ID and capture its value in this instance of record().
  currentRecordingId = currentRecordingId + 1
  const thisRecordingId = currentRecordingId

  // Originally the parameter was a dont_print boolean flag.
  // To keep the existing code compatible we take that case into account.
  if (typeof recOptions === 'boolean') {
    recOptions = { dont_print: recOptions }
  }

  recOptions = { ...defaultRecordOptions, ...recOptions }

  debug('start recording', thisRecordingId, recOptions)

  const {
    dont_print: dontPrint,
    enable_reqheaders_recording: enableReqHeadersRecording,
    logging,
    output_objects: outputObjects,
    use_separator: useSeparator,
  } = recOptions

  debug(thisRecordingId, 'restoring overridden requests before new overrides')
  //  To preserve backward compatibility (starting recording wasn't throwing if nock was already active)
  //  we restore any requests that may have been overridden by other parts of nock (e.g. intercept)
  //  NOTE: This is hacky as hell but it keeps the backward compatibility *and* allows correct
  //    behavior in the face of other modules also overriding ClientRequest.
  // common.restoreOverriddenRequests()
  //  We restore ClientRequest as it messes with recording of modules that also override ClientRequest (e.g. xhr2)
  restoreOverriddenClientRequest()

  //  We override the requests so that we can save information on them before executing.
  clientRequestInterceptor.apply()
  fetchRequestInterceptor.apply()
  clientRequestInterceptor.on(
    'response',
    async function ({ request, response }) {
      await recordResponse(request, response)
    },
  )
  fetchRequestInterceptor.on(
    'response',
    async function ({ request, response }) {
      // fetch decompresses the body automatically, so we need to recompress it
      const codings =
        response.headers
          .get('content-encoding')
          ?.toLowerCase()
          .split(',')
          .map(c => c.trim()) || []

      let body = await response.arrayBuffer()
      for (const coding of codings) {
        if (coding === 'gzip') {
          body = gzipSync(body)
        } else if (coding === 'deflate') {
          body = deflateSync(body)
        } else if (coding === 'br') {
          body = brotliCompressSync(body)
        }
      }

      await recordResponse(request, new Response(body, response))
    },
  )

  async function recordResponse(mswRequest, mswResponse) {
    const request = mswRequest.clone()
    const response = mswResponse.clone()
    const { options } = common.normalizeClientRequestArgs(request.url)
    options.method = request.method
    const proto = options.protocol.slice(0, -1)
    if (proto === 'https') {
      options.proto = 'https'
    }
    debug(thisRecordingId, proto, 'intercepted request ended')

    let reqheaders
    // Ignore request headers completely unless it was explicitly enabled by the user (see README)
    if (enableReqHeadersRecording) {
      // We never record user-agent headers as they are worse than useless -
      // they actually make testing more difficult without providing any benefit (see README)
      reqheaders = Object.fromEntries(request.headers.entries())
      common.deleteHeadersField(reqheaders, 'user-agent')
    }

    const headers = Object.fromEntries(response.headers.entries())
    const res = {
      statusCode: response.status,
      headers,
      rawHeaders: headers,
    }

    const generateFn = outputObjects
      ? generateRequestAndResponseObject
      : generateRequestAndResponse
    let out = generateFn({
      req: options,
      bodyChunks: [Buffer.from(await request.arrayBuffer())],
      options,
      res,
      dataChunks: [Buffer.from(await response.arrayBuffer())],
      reqheaders,
    })

    debug('out:', out)

    //  Check that the request was made during the current recording.
    //  If it hasn't then skip it. There is no other simple way to handle
    //  this as it depends on the timing of requests and responses. Throwing
    //  will make some recordings/unit tests fail randomly depending on how
    //  fast/slow the response arrived.
    //  If you are seeing this error then you need to make sure that all
    //  the requests made during a single recording session finish before
    //  ending the same recording session.
    if (thisRecordingId !== currentRecordingId) {
      debug('skipping recording of an out-of-order request', out)
      return
    }

    outputs.push(out)

    if (!dontPrint) {
      if (useSeparator) {
        if (typeof out !== 'string') {
          out = JSON.stringify(out, null, 2)
        }
        logging(SEPARATOR + out + SEPARATOR)
      } else {
        logging(out)
      }
    }

    debug('finished setting up intercepting')
  }
}

// Restore *all* the overridden http/https modules' properties.
function restore() {
  debug(
    currentRecordingId,
    'restoring all the overridden http/https properties',
  )

  clientRequestInterceptor.dispose()
  fetchRequestInterceptor.dispose()
  restoreOverriddenClientRequest()
  recordingInProgress = false
}

function clear() {
  outputs = []
}

module.exports = {
  record,
  outputs: () => outputs,
  restore,
  clear,
}