Fixes #2933. Add one more Stream.multi test

LibTest/async/Stream/Stream.multi_A01_t02.dart

@@ -0,0 +1,70 @@
+// Copyright (c) 2024, 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.
+
+/// @assertion @Since("2.9")
+///   Stream<T>.multi(
+///     void onListen( MultiStreamController<T> ), {
+///     bool isBroadcast = false,
+///   })
+/// Creates a multi-subscription stream.
+///
+/// Each time the created stream is listened to, the `onListen` callback is
+/// invoked with a new [MultiStreamController], which forwards events to the
+/// [StreamSubscription] returned by that [listen] call.
+///
+/// This allows each listener to be treated as an individual stream.
+///
+/// The [MultiStreamController] does not support reading its
+/// [StreamController.stream]. Setting its [StreamController.onListen] has no
+/// effect since the `onListen` callback is called instead, and the
+/// [StreamController.onListen] won't be called later. The controller acts like
+/// an asynchronous controller, but provides extra methods for delivering events
+/// synchronously.
+///
+/// If `isBroadcast` is set to true, the returned stream's [Stream.isBroadcast]
+/// will be true. This has no effect on the stream behavior, it is up to the
+/// `onListen` function to act like a broadcast stream if it claims to be one.
+///
+/// A multi-subscription stream can behave like any other stream. If the
+/// `onListen` callback throws on every call after the first, the stream behaves
+/// like a single-subscription stream. If the stream emits the same events to
+/// all current listeners, it behaves like a broadcast stream.
+///
+/// @description Checks that the `Stream.multi()` constructor creates a
+/// multi-subscription stream.
+/// @author sgrekhov22@gmail.com
+
+import "dart:async";
+import "../../../Utils/expect.dart";
+
+main() {
+  asyncStart(2);
+  int counter = 1;
+  var stream = Stream<int>.multi((controller) {
+    for (;;counter++) {
+      controller.add(counter);
+      if (counter % 5 == 0) {
+        counter++;
+        controller.close();
+        return;
+      }
+    }
+  });
+
+  int i = 1;
+  stream.listen((v) {
+    Expect.equals(v, i++);
+  }, onDone: () {
+    Expect.equals(6, i);
+    asyncEnd();
+  });
+
+  int j = 6;
+  stream.listen((v) {
+    Expect.equals(v, j++);
+  }, onDone: () {
+    Expect.equals(11, j);
+    asyncEnd();
+  });
+}