From cd9b0bf68c2c278c703c8993beed3029cddb41a8 Mon Sep 17 00:00:00 2001
From: James M Snell <jasnell@gmail.com>
Date: Wed, 11 Aug 2021 08:58:27 -0700
Subject: [PATCH] stream: ensure text() stream consumer flushes correctly

Signed-off-by: James M Snell <jasnell@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/39737
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
---
 lib/stream/consumers.js                |  3 +++
 test/parallel/test-stream-consumers.js | 14 ++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/lib/stream/consumers.js b/lib/stream/consumers.js
index ffe6e531205e7f..4566eff6a30f7f 100644
--- a/lib/stream/consumers.js
+++ b/lib/stream/consumers.js
@@ -63,6 +63,9 @@ async function text(stream) {
     else
       str += dec.decode(chunk, { stream: true });
   }
+  // Flush the streaming TextDecoder so that any pending
+  // incomplete multibyte characters are handled.
+  str += dec.decode(undefined, { stream: false });
   return str;
 }
 
diff --git a/test/parallel/test-stream-consumers.js b/test/parallel/test-stream-consumers.js
index 8f6a9deb1c27dc..1a3b6ce00200d4 100644
--- a/test/parallel/test-stream-consumers.js
+++ b/test/parallel/test-stream-consumers.js
@@ -232,3 +232,17 @@ const kArrayBuffer =
   stream.write({});
   stream.end({});
 }
+
+{
+  const stream = new TransformStream();
+  text(stream.readable).then(common.mustCall((str) => {
+    // Incomplete utf8 character is flushed as a replacement char
+    assert.strictEqual(str.charCodeAt(0), 0xfffd);
+  }));
+  const writer = stream.writable.getWriter();
+  Promise.all([
+    writer.write(new Uint8Array([0xe2])),
+    writer.write(new Uint8Array([0x82])),
+    writer.close(),
+  ]).then(common.mustCall());
+}