From 0cd01183342d0a1675a261c0bb57e742cfd75d7d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jes=C3=BAs=20Legan=C3=A9s=20Combarro=20=22piranna?=
 <piranna@gmail.com>
Date: Tue, 7 Jun 2016 22:54:51 +0200
Subject: [PATCH] stream: 'data' argument on callback of Transform._flush()

Add a `data` argument on Transform._flush() callback to be API
consistent with Transform._transform().

Fixes: https://github.com/nodejs/node/issues/3707
PR-URL: https://github.com/nodejs/node/pull/3708
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
---
 doc/api/stream.md                             |  2 +-
 lib/_stream_transform.js                      |  9 ++++---
 .../test-stream-transform-flush-data.js       | 27 +++++++++++++++++++
 3 files changed, 34 insertions(+), 4 deletions(-)
 create mode 100644 test/parallel/test-stream-transform-flush-data.js

diff --git a/doc/api/stream.md b/doc/api/stream.md
index 48c1a44eb6a258..c7aa8f24170647 100644
--- a/doc/api/stream.md
+++ b/doc/api/stream.md
@@ -1697,7 +1697,7 @@ after all data has been output, which occurs after the callback in
 #### transform.\_flush(callback)
 
 * `callback` {Function} A callback function (optionally with an error
-  argument) to be called when remaining data has been flushed.
+  argument and data) to be called when remaining data has been flushed.
 
 *Note*: **This function MUST NOT be called by application code directly.** It
 should be implemented by child classes, and called only by the internal Readable
diff --git a/lib/_stream_transform.js b/lib/_stream_transform.js
index 50fc542b5abd91..5dc7fdd0a8d831 100644
--- a/lib/_stream_transform.js
+++ b/lib/_stream_transform.js
@@ -115,8 +115,8 @@ function Transform(options) {
 
   this.once('prefinish', function() {
     if (typeof this._flush === 'function')
-      this._flush(function(er) {
-        done(stream, er);
+      this._flush(function(er, data) {
+        done(stream, er, data);
       });
     else
       done(stream);
@@ -173,10 +173,13 @@ Transform.prototype._read = function(n) {
 };
 
 
-function done(stream, er) {
+function done(stream, er, data) {
   if (er)
     return stream.emit('error', er);
 
+  if (data !== null && data !== undefined)
+    stream.push(data);
+
   // if there's nothing in the write buffer, then that means
   // that nothing more will ever be provided
   var ws = stream._writableState;
diff --git a/test/parallel/test-stream-transform-flush-data.js b/test/parallel/test-stream-transform-flush-data.js
new file mode 100644
index 00000000000000..dede64ba10f9da
--- /dev/null
+++ b/test/parallel/test-stream-transform-flush-data.js
@@ -0,0 +1,27 @@
+'use strict';
+
+require('../common');
+
+const assert = require('assert');
+const Transform = require('stream').Transform;
+
+
+const expected = 'asdf';
+
+
+function _transform(d, e, n) {
+  n();
+}
+function _flush(n) {
+  n(null, expected);
+}
+
+var t = new Transform({
+  transform: _transform,
+  flush: _flush
+});
+
+t.end(Buffer.from('blerg'));
+t.on('data', (data) => {
+  assert.strictEqual(data.toString(), expected);
+});