Don't wait unnecessarily.

tests/stub-generator/src/MintMakerPromiseWithStubsTest.dart

 // Copyright (c) 2011, 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.
 
 // IsolateStubs=MintMakerPromiseWithStubsTest.dart:Mint,Purse
 
 #import("../../isolate/src/TestFramework.dart");
 
 interface Mint factory MintImpl {
 
   Mint();
 
   Purse createPurse(int balance);
 
 }
 
 interface Purse factory PurseImpl {
 
   Purse();
 
   int queryBalance();
   Purse sproutPurse();
-  int deposit(int amount, Purse$Proxy source);
+  Promise<int> deposit(int amount, Purse$Proxy source);
 
 }
 
 class MintImpl implements Mint {
 
   MintImpl() { }
 
   Purse createPurse(int balance) {
     PurseImpl purse = new PurseImpl();
     purse.init(this, balance);
@@ skipping 16 matching lines @@
   }
 
   int queryBalance() {
     return _balance;
   }
 
   Purse sproutPurse() {
     return _mint.createPurse(0);
   }
 
-  int deposit(int amount, Purse$Proxy proxy) {
+  Promise<int> deposit(int amount, Purse$Proxy proxy) {
     if (amount < 0) throw "Ha ha";
     // Because we are in the same isolate as the other purse, we can
     // retrieve the proxy's local PurseImpl object and act on it
     // directly. Further, a forged purse will not be convertible, and
     // so an attempt to use it will fail.
-    PurseImpl source = proxy.dynamic.local;
-    if (source._balance < amount) throw "Not enough dough.";
-    _balance += amount;
-    source._balance -= amount;
-    return _balance;
+    Promise<int> balance = new Promise<int>();
+    proxy.addCompleteHandler((_) {
+      PurseImpl source = proxy.dynamic.local;
+      if (source._balance < amount) throw "Not enough dough.";
+      _balance += amount;
+      source._balance -= amount;
+      balance.complete(_balance);
+    });
+    return balance;
   }
 
   Mint _mint;
   int _balance;
 
 }
 
 class MintMakerPromiseWithStubsTest {
 
   static void testMain(TestExpectation expect) {
@@ skipping 20 matching lines @@
         });
     });
     expect.succeeded();
   }
 
 }
 
 main() {
   runTests([MintMakerPromiseWithStubsTest.testMain]);
 }