Refactor Future constructors.

utils/tests/pub/error_group_test.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 error_group_test;
 
 import 'dart:async';
 
 import 'package:unittest/unittest.dart';
 
@@ skipping 18 matching lines @@
     test('should pass signaled errors to .done', () {
       expect(errorGroup.done, throwsFormatException);
       errorGroup.signalError(new FormatException());
     });
 
     test("shouldn't allow additional futures or streams once an error has been "
         "signaled", () {
       expect(errorGroup.done, throwsFormatException);
       errorGroup.signalError(new FormatException());
 
-      expect(() => errorGroup.registerFuture(new Future.immediate(null)),
+      expect(() => errorGroup.registerFuture(new Future.value()),
           throwsStateError);
       expect(() => errorGroup.registerStream(new StreamController().stream),
           throwsStateError);
     });
   });
 
   group('with a single future', () {
     Completer completer;
     Future future;
 
     setUp(() {
       errorGroup = new ErrorGroup();
       completer = new Completer();
       future = errorGroup.registerFuture(completer.future);
     });
 
     test('should pass through a value from the future', () {
       expect(future, completion(equals('value')));
       expect(errorGroup.done, completes);
       completer.complete('value');
     });
 
     test("shouldn't allow additional futures or streams once .done has "
         "been called", () {
       completer.complete('value');
 
-      expect(() => errorGroup.registerFuture(new Future.immediate(null)),
+      expect(() => errorGroup.registerFuture(new Future.value()),
           throwsStateError);
       expect(() => errorGroup.registerStream(new StreamController().stream),
           throwsStateError);
     });
 
     test('should pass through an exception from the future if it has a '
         'listener', () {
       expect(future, throwsFormatException);
       // errorGroup shouldn't top-level the exception
       completer.completeError(new FormatException());
@@ skipping 343 matching lines @@
       expect(stream.toList(), completion(equals(['value1', 'value2'])));
       controller..add('value1')..add('value2')..close();
 
       expect(stream.toList().then((_) {
         // shouldn't cause a top-level exception
         completer.completeError(new FormatException());
       }), completes);
     });
   });
 }