stream: fix merge handling for object-like sources

merge() treated any final non-iterable object as an options object.
That dropped valid from() inputs such as ArrayBuffer, ArrayBufferView,
and streamable protocol objects.

Fixes: #63355

Signed-off-by: Kamat, Trivikram <16024985+trivikr@users.noreply.github.com>
Assisted-by: openai:gpt-5.5
PR-URL: #63356
Fixes: #63355
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: René <contact.9a5d6388@renegade334.me.uk>

Author: trivikr

lib/internal/streams/iter/consumers.js

@@ -8,6 +8,7 @@
 // ondrain() - backpressure drain utility
 
 const {
+  ArrayBufferIsView,
   ArrayBufferPrototypeGetByteLength,
   ArrayBufferPrototypeSlice,
   ArrayPrototypeMap,
@@ -51,9 +52,12 @@ const {
 
 const {
   drainableProtocol,
+  toAsyncStreamable,
+  toStreamable,
 } = require('internal/streams/iter/types');
 
 const {
+  isAnyArrayBuffer,
   isSharedArrayBuffer,
 } = require('internal/util/types');
 
@@ -65,8 +69,12 @@ function isMergeOptions(value) {
   return (
     value !== null &&
     typeof value === 'object' &&
+    !ArrayBufferIsView(value) &&
+    typeof value[toStreamable] !== 'function' &&
+    typeof value[toAsyncStreamable] !== 'function' &&
     !isAsyncIterable(value) &&
-    !isSyncIterable(value)
+    !isSyncIterable(value) &&
+    !isAnyArrayBuffer(value)
   );
 }
 

test/parallel/test-stream-iter-consumers-merge.js

@@ -9,6 +9,8 @@ const {
   push,
   merge,
   text,
+  toAsyncStreamable,
+  toStreamable,
 } = require('stream/iter');
 
 // =============================================================================
@@ -162,6 +164,27 @@ async function testMergeStringSources() {
   assert.ok(combined.includes('world'));
 }
 
+// merge() accepts object-like sources that are normalized via from()
+async function testMergeObjectLikeSources() {
+  const arrayBuffer = new TextEncoder().encode('abc').buffer;
+  const dataView = new DataView(new TextEncoder().encode('def').buffer);
+  const streamable = {
+    [toStreamable]() {
+      return 'ghi';
+    },
+  };
+  const asyncStreamable = {
+    [toAsyncStreamable]() {
+      return Promise.resolve('jkl');
+    },
+  };
+
+  assert.strictEqual(await text(merge(arrayBuffer)), 'abc');
+  assert.strictEqual(await text(merge(dataView)), 'def');
+  assert.strictEqual(await text(merge(streamable)), 'ghi');
+  assert.strictEqual(await text(merge(asyncStreamable)), 'jkl');
+}
+
 Promise.all([
   testMergeTwoSources(),
   testMergeSingleSource(),
@@ -172,4 +195,5 @@ Promise.all([
   testMergeConsumerBreak(),
   testMergeSignalMidIteration(),
   testMergeStringSources(),
+  testMergeObjectLikeSources(),
 ]).then(common.mustCall());