Bug 1826537 - Part 3: Add WebTransport stream test for being closed with no data r=smaug

To make sure the refactoring doesn't break it.

Differential Revision: https://phabricator.services.mozilla.com/D175254

testing/web-platform/meta/webtransport/streams-echo.https.any.js.ini

@@ -21,6 +21,9 @@
   [Transfer large chunks of data on a unidirectional stream]
     expected: [PASS, TIMEOUT, NOTRUN]
 
+  [Closing the stream with no data still resolves the read request]
+    expected: [PASS, TIMEOUT, NOTRUN]
+
 
 [streams-echo.https.any.worker.html]
   expected: [OK, TIMEOUT]
@@ -45,6 +48,9 @@
   [Transfer large chunks of data on a unidirectional stream]
     expected: [PASS, TIMEOUT, NOTRUN]
 
+  [Closing the stream with no data still resolves the read request]
+    expected: [PASS, TIMEOUT, NOTRUN]
+
 
 [streams-echo.https.any.sharedworker.html]
   expected: [OK, TIMEOUT]
@@ -69,6 +75,9 @@
   [Transfer large chunks of data on a unidirectional stream]
     expected: [PASS, TIMEOUT, NOTRUN]
 
+  [Closing the stream with no data still resolves the read request]
+    expected: [PASS, TIMEOUT, NOTRUN]
+
 
 [streams-echo.https.any.serviceworker.html]
   expected: [OK, TIMEOUT]
@@ -92,3 +101,6 @@
 
   [Transfer large chunks of data on a unidirectional stream]
     expected: [PASS, TIMEOUT, NOTRUN]
+
+  [Closing the stream with no data still resolves the read request]
+    expected: [PASS, TIMEOUT, NOTRUN]

testing/web-platform/tests/webtransport/streams-echo.https.any.js

@@ -213,3 +213,21 @@ promise_test(async t => {
   assert_equals(len, 3*bytes.length);
 }, 'Transfer large chunks of data on a unidirectional stream');
 
+promise_test(async t => {
+  // Establish a WebTransport session.
+  const wt = new WebTransport(webtransport_url('echo.py'));
+  await wt.ready;
+
+  // Create a bidirectional stream.
+  const bidi_stream = await wt.createBidirectionalStream();
+
+  // Close the writable end with no data at all.
+  const writer = bidi_stream.writable.getWriter();
+  writer.close();
+
+  // Read the data on the readable end.
+  const chunks = await read_stream(bidi_stream.readable);
+  assert_equals(chunks.length, 0);
+
+  await bidi_stream.readable.closed;
+}, 'Closing the stream with no data still resolves the read request');