feat: response.stream() (#284)

* feat: response.stream()

Provide `Readable` response through `response.stream()`

* Update README.md

Signed-off-by: Frazer Smith <frazer.dev@outlook.com>

---------

Signed-off-by: Frazer Smith <frazer.dev@outlook.com>
Co-authored-by: Frazer Smith <frazer.dev@outlook.com>

README.md

@@ -182,6 +182,7 @@ Injects a fake request into an HTTP server.
     - `rawPayload` - the raw payload as a Buffer.
     - `trailers` - an object containing the response trailers.
     - `json` - a function that parses a json response payload and returns an object.
+    - `stream` - a function that provides a `Readable` stream of the response payload.
     - `cookies` - a getter that parses the `set-cookie` response header and returns an array with all the cookies and their metadata.
 
 Notes:

lib/response.js

@@ -1,7 +1,7 @@
 'use strict'
 
 const http = require('node:http')
-const { Writable } = require('node:stream')
+const { Writable, Readable } = require('node:stream')
 const util = require('node:util')
 
 const setCookie = require('set-cookie-parser')
@@ -143,6 +143,11 @@ function generatePayload (response) {
     return JSON.parse(res.payload)
   }
 
+  // Provide stream Readable for advanced user
+  res.stream = function streamPayload () {
+    return Readable.from(response._lightMyRequest.payloadChunks)
+  }
+
   return res
 }
 

test/index.test.js

@@ -1421,6 +1421,38 @@ test('Response.json() should throw an error if the payload is not of valid JSON
   })
 })
 
+test('Response.stream() should provide a Readable stream', (t) => {
+  const lines = [
+    JSON.stringify({ foo: 'bar' }),
+    JSON.stringify({ hello: 'world' })
+  ]
+
+  t.plan(2 + lines.length)
+
+  const dispatch = function (req, res) {
+    res.writeHead(200, { 'Content-Type': 'multiple/json' })
+    for (const line of lines) {
+      res.write(line)
+    }
+    res.end()
+  }
+
+  inject(dispatch, { method: 'GET', path: 'http://example.com:8080/hello' }, (err, res) => {
+    t.error(err)
+    const readable = res.stream()
+    const payload = []
+    t.equal(readable instanceof Readable, true)
+    readable.on('data', function (chunk) {
+      payload.push(chunk)
+    })
+    readable.on('end', function () {
+      for (let i = 0; i < lines.length; i++) {
+        t.equal(lines[i], payload[i].toString())
+      }
+    })
+  })
+})
+
 test('promise api should auto start (fire and forget)', (t) => {
   t.plan(1)
 

types/index.d.ts

@@ -1,4 +1,5 @@
 import * as http from 'http'
+import { Readable } from 'stream'
 
 type HTTPMethods = 'DELETE' | 'delete' |
                    'GET' | 'get' |
@@ -87,6 +88,7 @@ declare namespace inject {
     payload: string
     body: string
     json: <T = any>() => T
+    stream: () => Readable
     cookies: Array<Cookie>
   }
 

types/index.test-d.ts

@@ -1,6 +1,7 @@
 import * as http from 'http'
 import { inject, isInjection, Response, DispatchFunc, InjectOptions, Chain } from '..'
 import { expectType, expectAssignable, expectNotAssignable } from 'tsd'
+import { Readable } from 'stream'
 
 expectAssignable<InjectOptions>({ url: '/' })
 expectAssignable<InjectOptions>({ autoStart: true })
@@ -26,8 +27,10 @@ const expectResponse = function (res: Response | undefined) {
   expectType<Response>(res)
   console.log(res.payload)
   expectAssignable<Function>(res.json)
+  expectAssignable<Function>(res.stream)
   expectAssignable<http.ServerResponse>(res.raw.res)
   expectAssignable<http.IncomingMessage>(res.raw.req)
+  expectType<Readable>(res.stream())
   expectType<string>(res.payload)
   expectType<string>(res.body)
   expectAssignable<Array<any>>(res.cookies)