Add payloadAsStream option

README.md

@@ -168,6 +168,7 @@ Injects a fake request into an HTTP server.
   - `signal` - An `AbortSignal` that may be used to abort an ongoing request. Requires Node v16+.
   - `Request` - Optional type from which the `request` object should inherit
     instead of `stream.Readable`
+  - `payloadAsStream` - if set to `true`, the response will be streamed and not accumulated; in this case `res.payload`, `res.rawPayload` will be undefined.
 - `callback` - the callback function using the signature `function (err, res)` where:
   - `err` - error object
   - `res` - a response object where:

lib/request.js

@@ -182,7 +182,9 @@ function Request (options) {
   this._lightMyRequest = {
     payload,
     isDone: false,
-    simulate: options.simulate || {}
+    simulate: options.simulate || {},
+    payloadAsStream: options.payloadAsStream,
+    signal: options.signal
   }
 
   const signal = options.signal

lib/response.js

@@ -1,15 +1,24 @@
 'use strict'
 
 const http = require('node:http')
-const { Writable, Readable } = require('node:stream')
+const { Writable, Readable, addAbortSignal } = require('node:stream')
 const util = require('node:util')
 
 const setCookie = require('set-cookie-parser')
 
 function Response (req, onEnd, reject) {
   http.ServerResponse.call(this, req)
 
-  this._lightMyRequest = { headers: null, trailers: {}, payloadChunks: [] }
+  if (req._lightMyRequest?.payloadAsStream) {
+    this._lightMyRequest = { headers: null, trailers: {}, stream: new Readable({ read () {} }) }
+    const signal = req._lightMyRequest.signal
+
+    if (signal) {
+      addAbortSignal(signal, this._lightMyRequest.stream)
+    }
+  } else {
+    this._lightMyRequest = { headers: null, trailers: {}, payloadChunks: [] }
+  }
   // This forces node@8 to always render the headers
   this.setHeader('foo', 'bar'); this.removeHeader('foo')
 
@@ -26,21 +35,37 @@ function Response (req, onEnd, reject) {
     }
     process.nextTick(() => onEnd(null, payload))
   }
+  this._lightMyRequest.onEndSuccess = onEndSuccess
 
   const onEndFailure = (err) => {
     if (called) return
     called = true
-    if (this._promiseCallback) {
-      return process.nextTick(() => reject(err))
+    if (this._lightMyRequest.stream) {
+      const res = generatePayload(this)
+      res.raw.req = req
+      this._lightMyRequest.stream._read = function () {
+        this.destroy(err || new Error('premature close'))
+      }
+      onEndSuccess(res)
+    } else {
+      if (this._promiseCallback) {
+        return process.nextTick(() => reject(err))
+      }
+      process.nextTick(() => onEnd(err, null))
     }
-    process.nextTick(() => onEnd(err, null))
   }
 
-  this.once('finish', () => {
-    const res = generatePayload(this)
-    res.raw.req = req
-    onEndSuccess(res)
-  })
+  if (this._lightMyRequest.stream) {
+    this.once('finish', () => {
+      this._lightMyRequest.stream.push(null)
+    })
+  } else {
+    this.once('finish', () => {
+      const res = generatePayload(this)
+      res.raw.req = req
+      onEndSuccess(res)
+    })
+  }
 
   this.connection.once('error', onEndFailure)
 
@@ -64,6 +89,10 @@ Response.prototype.writeHead = function () {
 
   copyHeaders(this)
 
+  if (this._lightMyRequest.stream) {
+    this._lightMyRequest.onEndSuccess(generatePayload(this))
+  }
+
   return result
 }
 
@@ -72,7 +101,11 @@ Response.prototype.write = function (data, encoding, callback) {
     clearTimeout(this.timeoutHandle)
   }
   http.ServerResponse.prototype.write.call(this, data, encoding, callback)
-  this._lightMyRequest.payloadChunks.push(Buffer.from(data, encoding))
+  if (this._lightMyRequest.stream) {
+    this._lightMyRequest.stream.push(Buffer.from(data, encoding))
+  } else {
+    this._lightMyRequest.payloadChunks.push(Buffer.from(data, encoding))
+  }
   return true
 }
 
@@ -129,22 +162,32 @@ function generatePayload (response) {
     }
   }
 
-  // Prepare payload and trailers
-  const rawBuffer = Buffer.concat(response._lightMyRequest.payloadChunks)
-  res.rawPayload = rawBuffer
-
-  // we keep both of them for compatibility reasons
-  res.payload = rawBuffer.toString()
-  res.body = res.payload
   res.trailers = response._lightMyRequest.trailers
 
-  // Prepare payload parsers
-  res.json = function parseJsonPayload () {
-    return JSON.parse(res.payload)
+  if (response._lightMyRequest.payloadChunks) {
+    // Prepare payload and trailers
+    const rawBuffer = Buffer.concat(response._lightMyRequest.payloadChunks)
+    res.rawPayload = rawBuffer
+
+    // we keep both of them for compatibility reasons
+    res.payload = rawBuffer.toString()
+    res.body = res.payload
+
+    // Prepare payload parsers
+    res.json = function parseJsonPayload () {
+      return JSON.parse(res.payload)
+    }
+  } else {
+    res.json = function () {
+      throw new Error('Response payload is not available with payloadAsStream: true')
+    }
   }
 
   // Provide stream Readable for advanced user
   res.stream = function streamPayload () {
+    if (response._lightMyRequest.stream) {
+      return response._lightMyRequest.stream
+    }
     return Readable.from(response._lightMyRequest.payloadChunks)
   }
 
@@ -179,7 +222,7 @@ function copyHeaders (response) {
   // Add raw headers
   ;['Date', 'Connection', 'Transfer-Encoding'].forEach((name) => {
     const regex = new RegExp('\\r\\n' + name + ': ([^\\r]*)\\r\\n')
-    const field = response._header.match(regex)
+    const field = response._header?.match(regex)
     if (field) {
       response._lightMyRequest.headers[name.toLowerCase()] = field[1]
     }