test: use drain() for discard loops in stream/iter tests

Replaces the `for await (const _ of source) {}` discard idiom with
drain(), which says what it does and does not need an eslint-disable
for the unused loop variable. 89 loops across 60 files, plus 32 now
redundant eslint-disable directives and comments removed.

Only files that already declare --experimental-stream-iter are
converted, so no test gains an experimental flag it did not already
opt into. That leaves 19 files with the old idiom; converting those
would change what those tests run under and belongs in a separate
discussion.

Loops that break early are left alone: those cancel the source rather
than reading it to completion, which is not what drain() does.

Four QUIC tests already bound a local `drain` to the writer-side
drainableProtocol promise. Those locals are renamed to drainPromise;
in test-quic-stream-writer-api.mjs the local shadowed the import and
broke at runtime rather than at parse time.

Assisted-by: Claude Opus 5
Signed-off-by: Ethan Arrowood <ethan@arrowood.dev>

Author: Ethan-Arrowood

test/parallel/test-quic-cc-algorithm.mjs

@@ -6,6 +6,7 @@
 
 import { hasQuic, skip, mustCall } from '../common/index.mjs';
 import assert from 'node:assert';
+import { drain } from 'node:stream/iter';
 
 if (!hasQuic) {
   skip('QUIC is not enabled');
@@ -39,7 +40,7 @@ for (const cc of ['reno', 'cubic', 'bbr']) {
     body: encoder.encode('congestion control test'),
   });
 
-  for await (const _ of stream) { /* drain */ } // eslint-disable-line no-unused-vars
+  await drain(stream);
   await Promise.all([stream.closed, serverDone.promise]);
 
   // Verify the session stats show congestion control was active.

test/parallel/test-quic-datagram-multiple.mjs

@@ -10,6 +10,7 @@
 import { hasQuic, skip, mustCall, mustCallAtLeast } from '../common/index.mjs';
 import assert from 'node:assert';
 import * as fixtures from '../common/fixtures.mjs';
+import { drain } from 'node:stream/iter';
 
 if (!hasQuic) {
   skip('QUIC is not enabled');
@@ -72,7 +73,7 @@ for (let i = 0; i < numDatagrams; i++) {
 }
 
 // Complete the stream.
-for await (const _ of stream) { /* drain */ } // eslint-disable-line no-unused-vars
+await drain(stream);
 await stream.closed;
 
 // At least some datagrams should have arrived.

test/parallel/test-quic-diagnostics-channel-stream.mjs

@@ -9,6 +9,7 @@
 import { hasQuic, skip, mustCall } from '../common/index.mjs';
 import assert from 'node:assert';
 import dc from 'node:diagnostics_channel';
+import { drain } from 'node:stream/iter';
 
 if (!hasQuic) {
   skip('QUIC is not enabled');
@@ -59,7 +60,7 @@ const stream = await clientSession.createBidirectionalStream({
   body: encoder.encode('diagnostics test'),
 });
 
-for await (const _ of stream) { /* drain */ } // eslint-disable-line no-unused-vars
+await drain(stream);
 
 await Promise.all([stream.closed, serverDone.promise, clientSession.closed]);
 await serverEndpoint.close();

test/parallel/test-quic-flow-control-blob.mjs

@@ -7,6 +7,7 @@
 
 import { hasQuic, skip, mustCall } from '../common/index.mjs';
 import assert from 'node:assert';
+import { drain } from 'node:stream/iter';
 
 if (!hasQuic) {
   skip('QUIC is not enabled');
@@ -42,7 +43,7 @@ const stream = await clientSession.createBidirectionalStream({
   body: blob,
 });
 
-for await (const _ of stream) { /* drain */ } // eslint-disable-line no-unused-vars
+await drain(stream);
 await Promise.all([stream.closed, serverDone.promise]);
 await clientSession.close();
 await serverEndpoint.close();

test/parallel/test-quic-flow-control-block-resume.mjs

@@ -8,6 +8,7 @@
 
 import { hasQuic, skip, mustCall } from '../common/index.mjs';
 import assert from 'node:assert';
+import { drain } from 'node:stream/iter';
 
 if (!hasQuic) {
   skip('QUIC is not enabled');
@@ -43,7 +44,7 @@ await clientSession.opened;
 const stream = await clientSession.createBidirectionalStream();
 stream.setBody(data);
 
-for await (const _ of stream) { /* drain */ } // eslint-disable-line no-unused-vars
+await drain(stream);
 
 await Promise.all([stream.closed, serverDone.promise, clientSession.closed]);
 

test/parallel/test-quic-flow-control-params.mjs

@@ -12,6 +12,7 @@
 
 import { hasQuic, skip, mustCall } from '../common/index.mjs';
 import assert from 'node:assert';
+import { drain } from 'node:stream/iter';
 
 if (!hasQuic) {
   skip('QUIC is not enabled');
@@ -57,13 +58,13 @@ const encoder = new TextEncoder();
   for (let offset = 0; offset < expected.byteLength; offset += chunkSize) {
     const chunk = expected.slice(offset, offset + chunkSize);
     while (!w.writeSync(chunk)) {
-      const drain = w[dp]();
-      if (drain) await drain;
+      const drainPromise = w[dp]();
+      if (drainPromise) await drainPromise;
     }
   }
   w.endSync();
 
-  for await (const _ of stream) { /* drain */ } // eslint-disable-line no-unused-vars
+  await drain(stream);
   await Promise.all([stream.closed, serverDone.promise]);
   await clientSession.close();
   await serverEndpoint.close();

test/parallel/test-quic-h3-maxstreamdata-external-buffer-failure.mjs

@@ -7,6 +7,7 @@
 import { hasQuic, skip } from '../common/index.mjs';
 import { readFile } from 'node:fs/promises';
 import { setTimeout as sleep } from 'node:timers/promises';
+import { drain } from 'node:stream/iter';
 
 if (!hasQuic) {
   skip('QUIC is not enabled');
@@ -33,8 +34,8 @@ const serverMayRead = new Promise((resolve) => { letServerRead = resolve; });
 const endpoint = await listen((session) => {
   session.onstream = async (stream) => {
     await serverMayRead;
-    // eslint-disable-next-line no-unused-vars
-    for await (const _ of stream) { /* reading extends the window */ }
+    // Reading extends the window
+    await drain(stream);
   };
 }, {
   sni: { '*': { keys: [key], certs: [cert] } },

test/parallel/test-quic-key-update-peer.mjs

@@ -6,6 +6,7 @@
 
 import { hasQuic, skip, mustCall } from '../common/index.mjs';
 import assert from 'node:assert';
+import { drain } from 'node:stream/iter';
 
 if (!hasQuic) {
   skip('QUIC is not enabled');
@@ -41,7 +42,7 @@ await clientSession.opened;
 const stream = await clientSession.createBidirectionalStream({
   body: encoder.encode('after key update'),
 });
-for await (const _ of stream) { /* drain */ } // eslint-disable-line no-unused-vars
+await drain(stream);
 await Promise.all([stream.closed, serverDone.promise]);
 
 await clientSession.closed;

test/parallel/test-quic-key-update.mjs

@@ -7,6 +7,7 @@
 
 import { hasQuic, skip, mustCall } from '../common/index.mjs';
 import assert from 'node:assert';
+import { drain } from 'node:stream/iter';
 
 if (!hasQuic) {
   skip('QUIC is not enabled');
@@ -42,7 +43,7 @@ clientSession.updateKey();
 const stream = await clientSession.createBidirectionalStream();
 stream.setBody(data);
 
-for await (const _ of stream) { /* drain */ } // eslint-disable-line no-unused-vars
+await drain(stream);
 await Promise.all([stream.closed, serverDone.promise]);
 await clientSession.close();
 await serverEndpoint.close();

test/parallel/test-quic-max-payload-size.mjs

@@ -7,6 +7,7 @@
 
 import { hasQuic, skip, mustCall } from '../common/index.mjs';
 import assert from 'node:assert';
+import { drain } from 'node:stream/iter';
 
 if (!hasQuic) {
   skip('QUIC is not enabled');
@@ -38,7 +39,7 @@ async function transferAndGetPacketCount(maxPayloadSize) {
 
   const stream = await clientSession.createBidirectionalStream();
   stream.setBody(new Uint8Array(dataLength));
-  for await (const _ of stream) { /* drain */ } // eslint-disable-line no-unused-vars
+  await drain(stream);
   await Promise.all([stream.closed, serverDone.promise]);
 
   const pktSent = clientSession.stats.pktSent;