From 1b47866a1d94224678ce05e7c7355ff17ad9cce6 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Fri, 25 Feb 2022 14:31:20 +0100
Subject: [PATCH] stream: allow returning null from pipeline tail

PR-URL: https://github.com/nodejs/node/pull/42078
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
---
 lib/internal/streams/pipeline.js      |  4 +++-
 test/parallel/test-stream-pipeline.js | 15 +++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/internal/streams/pipeline.js b/lib/internal/streams/pipeline.js
index 36e1aebdd10e10..a3f69c2099ace1 100644
--- a/lib/internal/streams/pipeline.js
+++ b/lib/internal/streams/pipeline.js
@@ -288,7 +288,9 @@ function pipelineImpl(streams, callback, opts) {
           then.call(ret,
                     (val) => {
                       value = val;
-                      pt.write(val);
+                      if (val != null) {
+                        pt.write(val);
+                      }
                       if (end) {
                         pt.end();
                       }
diff --git a/test/parallel/test-stream-pipeline.js b/test/parallel/test-stream-pipeline.js
index 1948eeef8af257..eecf836b5bb77f 100644
--- a/test/parallel/test-stream-pipeline.js
+++ b/test/parallel/test-stream-pipeline.js
@@ -1511,3 +1511,18 @@ const tsp = require('timers/promises');
     assert.strictEqual(s.destroyed, true);
   }));
 }
+
+{
+  const s = new PassThrough({ objectMode: true });
+  pipeline(async function*() {
+    await Promise.resolve();
+    yield 'hello';
+    yield 'world';
+    yield 'world';
+  }, s, async function(source) {
+    return null;
+  }, common.mustCall((err, val) => {
+    assert.strictEqual(err, undefined);
+    assert.strictEqual(val, null);
+  }));
+}