|  | // 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. | 
|  |  | 
|  | import "package:expect/expect.dart"; | 
|  |  | 
|  | class Mixin { | 
|  | var field; | 
|  | createIt() { | 
|  | if (field == null) field = 42; | 
|  | } | 
|  | } | 
|  |  | 
|  | class A { | 
|  | A(foo); | 
|  | } | 
|  |  | 
|  | class B extends A with Mixin { | 
|  | // Because [super] references a synthesized constructor, dart2js | 
|  | // used to not see the null assignment to it. | 
|  | B(foo) : super(foo); | 
|  | } | 
|  |  | 
|  | main() { | 
|  | var a = new B(42); | 
|  | a.createIt(); | 
|  | Expect.equals(42, a.field); | 
|  | } |