From 00aaf1708de8185dc5312e66fda7c2a7d55206be Mon Sep 17 00:00:00 2001
From: Florian Loitsch <floitsch@google.com>
Date: Mon, 17 Aug 2015 11:34:43 +0200
Subject: [PATCH] Accept a computation that returns a Future for
 Future.delayed.

R=lrn@google.com

Review URL: https://codereview.chromium.org//1296623004 .
---
 sdk/lib/async/future.dart                     |  2 +-
 tests/lib/async/future_constructor2_test.dart | 62 +++++++++++++++++++
 2 files changed, 63 insertions(+), 1 deletion(-)
 create mode 100644 tests/lib/async/future_constructor2_test.dart

diff --git a/sdk/lib/async/future.dart b/sdk/lib/async/future.dart
index 5d6a65009a4..30016f7acc8 100644
--- a/sdk/lib/async/future.dart
+++ b/sdk/lib/async/future.dart
@@ -221,7 +221,7 @@ abstract class Future<T> {
    * See also [Completer] for a way to create and complete a future at a
    * later time that isn't necessarily after a known fixed duration.
    */
-  factory Future.delayed(Duration duration, [T computation()]) {
+  factory Future.delayed(Duration duration, [computation()]) {
     _Future result = new _Future<T>();
     new Timer(duration, () {
       try {
diff --git a/tests/lib/async/future_constructor2_test.dart b/tests/lib/async/future_constructor2_test.dart
new file mode 100644
index 00000000000..2d64ff4e965
--- /dev/null
+++ b/tests/lib/async/future_constructor2_test.dart
@@ -0,0 +1,62 @@
+// Copyright (c) 2015, 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.
+
+library future_delayed_test;
+
+import 'package:async_helper/async_helper.dart';
+import "package:expect/expect.dart";
+import 'dart:async';
+
+Future<int> createIntFuture() {
+  return new Future<int>.value(499);
+}
+
+unnamed() {
+  asyncStart();
+  new Future<int>(createIntFuture)
+      .then((x) {
+    Expect.equals(499, x);
+    asyncEnd();
+  });
+}
+
+delayed() {
+  asyncStart();
+  new Future<int>.delayed(const Duration(milliseconds: 2), createIntFuture)
+      .then((x) {
+    Expect.equals(499, x);
+    asyncEnd();
+  });
+}
+
+microtask() {
+  asyncStart();
+  new Future<int>.microtask(createIntFuture)
+      .then((x) {
+    Expect.equals(499, x);
+    asyncEnd();
+  });
+}
+
+sync() {
+  asyncStart();
+  new Future<int>.sync(createIntFuture)
+      .then((x) {
+    Expect.equals(499, x);
+    asyncEnd();
+  });
+}
+
+main() {
+  asyncStart();
+  // Test that all the Future constructors take functions that return a Future
+  // as argument.
+  // In particular the constructors must not type their argument as
+  // `T computation()`.
+  unnamed();
+  delayed();
+  microtask();
+  sync();
+  asyncEnd();
+}