feat(random): Added RandomStream

README.md

@@ -56,4 +56,10 @@ size in bytes of the stream.
 `new SizeStream()`
 
 If passed a callback `new SizeStream(cb)` it will just act as a
-PassThrough stream and call the callback when it's done.
+PassThrough stream and call the callback when it's done.
+
+### RandomStream
+
+`new RandomStream(max)`
+
+Readable stream that emits `max` random bytes before ending.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "common-streams",
-  "version": "1.0.1",
+  "version": "1.1.0",
   "description": "",
   "main": "./lib/index.js",
   "directories": {

src/RandomStream.js

@@ -0,0 +1,20 @@
+import { Readable } from 'stream'
+import { randomBytes } from 'crypto'
+
+export default class RandomStream extends Readable {
+  constructor(max) {
+    super()
+    this.remainingBytes = max
+  }
+  _read(requestedSize) {
+    if (this.remainingBytes === 0) return this.push(null)
+
+    const size = Math.min(this.remainingBytes, requestedSize)
+    this.remainingBytes -= size
+
+    randomBytes(size, (err, buf) => {
+      if (err) return this.emit('error', err)
+      this.push(buf)
+    })
+  }
+}

src/index.js

@@ -1,2 +1,3 @@
 export { default as HashStream } from './HashStream'
 export { default as SizeStream } from './SizeStream'
+export { default as RandomStream } from './RandomStream'

test/random.test.js

@@ -0,0 +1,22 @@
+import test from 'blue-tape'
+import concat from 'concat-stream'
+
+import { RandomStream } from '../src/'
+
+test('random stream', (t) => {
+  const rand = new RandomStream(10)
+
+  rand.pipe(concat((buf) => {
+    t.equal(buf.length, 10)
+    t.end()
+  }))
+})
+
+test('random stream #2', (t) => {
+  const rand = new RandomStream(2000)
+
+  rand.pipe(concat((buf) => {
+    t.equal(buf.length, 2000)
+    t.end()
+  }))
+})