test: Fix many_pending_secure_sockets_test timeouts.

Bug:https://github.com/dart-lang/sdk/issues/62064
Change-Id: Ie3aafd9549d7c26494faa7dddba85025e4b2cb69
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/465462
Commit-Queue: Brian Quinlan <bquinlan@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>

tests/standalone/io/many_pending_secure_sockets_test.dart

@@ -1,30 +1,87 @@
 // Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
+//
+// VMOptions=
+// VMOptions=--short_socket_read
+// VMOptions=--short_socket_write
+// VMOptions=--short_socket_read --short_socket_write
+// OtherResources=certificates/server_chain.pem
+// OtherResources=certificates/server_key.pem
+// OtherResources=certificates/trusted_certs.pem
 
-// https://github.com/flutter/flutter/issues/170723
+// Verifies that a large number of secure sockets can be connected
+// simultaneously.
+//
+// See https://github.com/flutter/flutter/issues/170723
 
+import 'dart:async';
 import "dart:io";
 
-test(int i) async {
-  try {
-    var socket = await RawSecureSocket.connect("www.google.com", 443);
-    await Future.delayed(
-      Duration(seconds: 6), // More than the thread pool timeout.
-    );
-    socket.close();
-  } catch (e, st) {
-    // Ignore failures from the remote side rejecting/closing the connection.
-    if (!e.toString().contains("Connection reset by peer")) {
-      rethrow;
-    }
-  }
+// Should be more than the number of threads that the OS can easily create.
+const numConnections = 2000;
+
+String localFile(path) => Platform.script.resolve(path).toFilePath();
+
+SecurityContext serverContext = new SecurityContext()
+  ..useCertificateChain(localFile('certificates/server_chain.pem'))
+  ..usePrivateKey(
+    localFile('certificates/server_key.pem'),
+    password: 'dartdart',
+  );
+SecurityContext clientContext = new SecurityContext()
+  ..setTrustedCertificates(localFile('certificates/trusted_certs.pem'));
+
+Future<SecureServerSocket> startServer() async {
+  final server = await SecureServerSocket.bind(
+    InternetAddress.loopbackIPv4,
+    0,
+    serverContext,
+  );
+  server.listen((SecureSocket client) async {
+    client.write('Connected!');
+    await client.flush();
+    client.listen((_) {}, onDone: () => client.close());
+  });
+  return server;
+}
+
+Future<RawSecureSocket> connectSocket(int port) async {
+  final socket = await RawSecureSocket.connect(
+    InternetAddress.loopbackIPv4,
+    port,
+    context: clientContext,
+  );
+  await socket.firstWhere((e) => e == RawSocketEvent.read);
+  return socket;
 }
 
 main() async {
-  var tests = <Future>[];
-  for (var i = 0; i < 2000; i++) {
-    tests.add(test(i));
+  final server = await startServer();
+  final tests = <Future>[];
+  final allConnected = Completer<void>();
+
+  for (var i = 0; i < numConnections;) {
+    // Performing thousands of simultaneous TLS connections can result in
+    // timeouts. So connect 20 sockets at a time.
+    final socketConnections = <Future<RawSecureSocket>>[];
+    for (var j = 0; i < numConnections && j < 20; i++, j++) {
+      socketConnections.add(connectSocket(server.port));
+    }
+
+    for (var socket in await Future.wait(socketConnections)) {
+      Future<void> delayAndClose() async {
+        await allConnected.future;
+        await Future.delayed(
+          Duration(seconds: 6), // More than the thread pool timeout.
+        );
+        socket.close();
+      }
+
+      tests.add(delayAndClose());
+    }
   }
+  allConnected.complete();
   await Future.wait(tests);
+  server.close();
 }

tests/standalone/standalone.status

@@ -8,6 +8,7 @@
 io/http_close_stack_overflow_test: Skip # The test is heavy loaded. Should be used for manual test.
 io/http_linklocal_ipv6_test: SkipByDesign # This needs manual test.
 io/large_file_read_small_file_test: Slow, Pass # Test reads small file 1M times
+io/many_pending_secure_sockets_test: Slow, Pass # Creates many TLS connections.
 io/non_utf8_directory_test: Skip # Issue 33519. Temp files causing bots to go purple.
 io/non_utf8_file_test: Skip # Issue 33519. Temp files causing bots to go purple.
 io/non_utf8_link_test: Skip # Issue 33519. Temp files causing bots to go purple.