Make a Future returned by the action of Future.whenCompelete delay.

tests/lib/async/future_test.dart

 // Copyright (c) 2012, 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_test;
 
 import 'dart:async';
 import 'dart:isolate';
 
 testImmediate() {
@@ skipping 323 matching lines @@
   completer.complete(42);
   new Timer(0, () {
     Future later = future.whenComplete(countDown);
     later.then((v) {
       Expect.equals(42, v);
       countDown();
     });
   });
 }
 
+testFutureWhenValueFutureValue() {
+  var port = new ReceivePort();
+  int counter = 3;
+  countDown(int expect) {
+    Expect.equals(expect, counter);
+    if (--counter == 0) port.close();
+  }
+  var completer = new Completer();
+  completer.future.whenComplete(() {
+    countDown(3);
+    var completer2 = new Completer();
+    new Timer(10, (_) {
+      countDown(2);
+      completer2.complete(37);
+    });
+    return completer2.future;
+  }).then((v) {
+    Expect.equals(42, v);
+    countDown(1);
+  });
+
+  completer.complete(42);
+}
+
+testFutureWhenValueFutureError() {
+  var port = new ReceivePort();
+  int counter = 3;
+  countDown(int expect) {
+    Expect.equals(expect, counter);
+    if (--counter == 0) port.close();
+  }
+  var completer = new Completer();
+  completer.future.whenComplete(() {
+    countDown(3);
+    var completer2 = new Completer();
+    new Timer(10, (_) {
+      countDown(2);
+      completer2.completeError("Fail");
+    });
+    return completer2.future;
+  }).then((v) {
+    Expect.fail("should fail async");
+  }, onError: (AsyncError e) {
+    Expect.equals("Fail", e.error);
+    countDown(1);
+  });
+
+  completer.complete(42);
+}
+
+testFutureWhenErrorFutureValue() {
+  var port = new ReceivePort();
+  int counter = 3;
+  countDown(int expect) {
+    Expect.equals(expect, counter);
+    if (--counter == 0) port.close();
+  }
+  var completer = new Completer();
+  completer.future.whenComplete(() {
+    countDown(3);
+    var completer2 = new Completer();
+    new Timer(10, (_) {
+      countDown(2);
+      completer2.complete(37);
+    });
+    return completer2.future;
+  }).then((v) {
+    Expect.fail("should fail async");
+  }, onError: (AsyncError e) {
+    Expect.equals("Error", e.error);
+    countDown(1);
+  });
+
+  completer.completeError("Error");
+}
+
+testFutureWhenErrorFutureError() {
+  var port = new ReceivePort();
+  int counter = 3;
+  countDown(int expect) {
+    Expect.equals(expect, counter);
+    if (--counter == 0) port.close();
+  }
+  var completer = new Completer();
+  completer.future.whenComplete(() {
+    countDown(3);
+    var completer2 = new Completer();
+    new Timer(10, (_) {
+      countDown(2);
+      completer2.completeError("Fail");
+    });
+    return completer2.future;
+  }).then((v) {
+    Expect.fail("should fail async");
+  }, onError: (AsyncError e) {
+    Expect.equals("Fail", e.error);
+    countDown(1);
+  });
+
+  completer.completeError("Error");
+}
+
+
+
 main() {
   testImmediate();
   testNeverComplete();
 
   testComplete();
   testCompleteWithSuccessHandlerBeforeComplete();
   testCompleteWithSuccessHandlerAfterComplete();
   testCompleteManySuccessHandlers();
 
   testException();
   testExceptionHandler();
   testExceptionHandlerReturnsTrue();
   testExceptionHandlerReturnsTrue2();
   testExceptionHandlerReturnsFalse();
 
   testFutureAsStreamCompleteAfter();
   testFutureAsStreamCompleteBefore();
   testFutureAsStreamCompleteImmediate();
   testFutureAsStreamCompleteErrorAfter();
   testFutureAsStreamWrapper();
 
   testFutureWhenCompleteValue();
   testFutureWhenCompleteError();
   testFutureWhenCompleteValueNewError();
   testFutureWhenCompleteErrorNewError();
+
+  testFutureWhenValueFutureValue();
+  testFutureWhenErrorFutureValue();
+  testFutureWhenValueFutureError();
+  testFutureWhenErrorFutureError();
 }