Re-submit r18349.

pkg/scheduled_test/lib/src/utils.dart

 // Copyright (c) 2013, 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 utils;
 
 import 'dart:async';
 
 /// Configures [future] so that its result (success or exception) is passed on
 /// to [completer].
 void chainToCompleter(Future future, Completer completer) {
   future.then((value) => completer.complete(value),
       onError: (e) => completer.completeError(e.error, e.stackTrace));
 }
 
 /// Prepends each line in [text] with [prefix].
 String prefixLines(String text, {String prefix: '| '}) =>
   text.split('\n').map((line) => '$prefix$line').join('\n');
 
-/// Returns a [Future] that completes in [milliseconds].
+/// Returns a [Future] that completes in at least [milliseconds].
+///
+/// This pumps the event loop after every second of sleeping. This should ensure

[Bob Nystrom, 2013/02/12 00:35:19]

second -> millisecond.

[nweiz, 2013/02/12 00:52:19]

Done.

+/// that even if the CPU is pegged and code is running much slower than
+/// expected, the sleep will take longer than any non-sleep code that's running.
 Future sleep(int milliseconds) {
+  if (milliseconds == 0) return new Future.immediate(null);
+  return _sleep1().then((_) => sleep(milliseconds - 1));
+}
+
+/// Returns a [Future] that completes in one millisecond.
+Future _sleep1() {
   var completer = new Completer();
-  new Timer(milliseconds, (_) => completer.complete());
+  new Timer(1, (_) => completer.complete());
   return completer.future;
 }
 
 /// Wraps [input] to provide a timeout. If [input] completes before
 /// [milliseconds] have passed, then the return value completes in the same way.
 /// However, if [milliseconds] pass before [input] has completed, [onTimeout] is
 /// run and its result is passed to [input] (with chaining, if it returns a
 /// [Future]).
 ///
 /// Note that timing out will not cancel the asynchronous operation behind
@@ skipping 10 matching lines @@
     if (completed) return;
     timer.cancel();
     completer.complete(value);
   }).catchError((e) {
     if (completed) return;
     timer.cancel();
     completer.completeError(e.error, e.stackTrace);
   });
   return completer.future;
 }