Use runAsync for Futures.

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';
 
 import 'package:stack_trace/stack_trace.dart';
 
@@ skipping 34 matching lines @@
   lines = lines.skip(1).map((line) => '$prefix$line').toList();
   lines.insert(0, firstLine);
   return lines.join('\n');
 }
 
 /// Returns a [Future] that completes after pumping the event queue [times]
 /// times. By default, this should pump the event queue enough times to allow
 /// any code to run, as long as it's not waiting on some external event.
 Future pumpEventQueue([int times=20]) {
   if (times == 0) return new Future.value();
-  return new Future.value().then((_) => pumpEventQueue(times - 1));
+  // We use a delayed future to allow runAsync events to finish. The
+  // Future.value or Future() constructors use runAsync themselves and would
+  // therefore not wait for runAsync callbacks that are scheduled after invoking
+  // this method.
+  return new Future.delayed(Duration.ZERO, () => pumpEventQueue(times - 1));
 }
 
 /// Returns whether [iterable1] has the same elements in the same order as
 /// [iterable2]. The elements are compared using `==`.
 bool orderedIterableEquals(Iterable iterable1, Iterable iterable2) {
   var iter1 = iterable1.iterator;
   var iter2 = iterable2.iterator;
 
   while (true) {
     var hasNext1 = iter1.moveNext();
@@ skipping 122 matching lines @@
 }
 
 /// Returns a string representation of [trace] that has the core and test frames
 /// folded together.
 String terseTraceString(StackTrace trace) {
   return new Trace.from(trace).terse.foldFrames((frame) {
     return frame.package == 'scheduled_test' || frame.package == 'unittest' ||
         frame.isCore;
   }).toString().trim();
 }