anchor.diff:      FakeWatcher.notifyWatchers(
         new WatchEvent(ChangeType.ADD, '$path/web/new.txt'),
       );
  -    await nextBuild.future;
  +    var result = await nextBuild.future;
  +    for (var output in result.outputs) {
  +      reader.cacheStringAsset(output, writer.assets[output].stringValue);
  +    }
       final response = await handler(new Request('GET', getNew));
       expect(await response.readAsString(), 'NEW');
  -  }, skip: 'Enable on fix of https://github.com/dart-lang/build/issues/500');
  +  });
   }
   
   class UppercaseBuilder implements Builder {
  
positive.code:   InMemoryRunnerAssetReader reader;
    InMemoryRunnerAssetWriter writer;
    StreamSubscription subscription;
    Completer<Null> nextBuild;
  
    final path = p.absolute('example');
  
  
negative.code:     ));
      handler = server.handlerFor('web');
  
      nextBuild = new Completer<BuildResult>();
      subscription = server.buildResults.listen((result) {
        nextBuild.complete(result);
        nextBuild = new Completer<BuildResult>();
      });
      await nextBuild.future;
    });
  