Add test for whether a completer or stream controller has been closed.

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';
 
 const Duration MS = const Duration(milliseconds: 1);
@@ skipping 35 matching lines @@
 testNeverComplete() {
   final completer = new Completer<int>();
   final future = completer.future;
   future.then((v) => Expect.fails("Value not expected"));
   future.catchError((e) => Expect.fails("Value not expected"));
 }
 
 testComplete() {
   final completer = new Completer<int>();
   final future = completer.future;
+  Expect.isFalse(completer.completed);
 
   completer.complete(3);
+  Expect.isTrue(completer.completed);
 
   future.then((v) => Expect.equals(3, v));
 }
 
 // Tests for [then]
 
 testCompleteWithSuccessHandlerBeforeComplete() {
   final completer = new Completer<int>();
   final future = completer.future;
 
   int value;
   future.then((int v) { value = v; });
   Expect.isNull(value);
+
+  Expect.isFalse(completer.completed);
   completer.complete(3);
+  Expect.isTrue(completer.completed);
 
   Expect.equals(3, value);
 }
 
 testCompleteWithSuccessHandlerAfterComplete() {
   final completer = new Completer<int>();
   final future = completer.future;
 
   int after;
   completer.complete(3);
@@ skipping 46 matching lines @@
   completer.completeError(ex);
 }
 
 testExceptionHandler() {
   final completer = new Completer<int>();
   final future = completer.future;
   final ex = new Exception();
 
   var ex2;
   var done = future.catchError((e) { ex2 = e.error; });
+
+  Expect.isFalse(completer.completed);
   completer.completeError(ex);
+  Expect.isTrue(completer.completed);
 
   var port = new ReceivePort();
   done.then((_) {
     Expect.equals(ex, ex2);
     port.close();
   });
 }
 
 testExceptionHandlerReturnsTrue() {
   final completer = new Completer<int>();
   final future = completer.future;
   final ex = new Exception();
 
   bool reached = false;
   future.catchError((e) { });
   future.catchError((e) { reached = true; }, test: (e) => false)
         .catchError((e) {});
+  Expect.isFalse(completer.completed);
   completer.completeError(ex);
+  Expect.isTrue(completer.completed);
   Expect.isFalse(reached);
 }
 
 testExceptionHandlerReturnsTrue2() {
   final completer = new Completer<int>();
   final future = completer.future;
   final ex = new Exception();
 
   bool reached = false;
   var done = future
@@ skipping 465 matching lines @@
   testFutureCatchThrowsAsync();
   testFutureWhenThrowsAsync();
   testFutureCatchRethrowsAsync();
 
   testChainedFutureValue();
   testChainedFutureValueDelay();
   testChainedFutureError();
 }