anchor.diff:          test("change and input event", () {
             var template =
                 dom.document.querySelector("#changeAndInputEventTemplate") as AutoBindingElement;
  -          var changeCalled = expectAsync((){}, id: "change event handler called");
  -          var inputCalled = expectAsync((){}, id: "input event handler called");
             var model = template.model = new MyModel()
  -              ..changeHandler = (e) {
  -                changeCalled();
  -              }
  -              ..inputHandler = (e) {
  -                inputCalled();
  -              };
  +              ..changeHandler = expectAsync((e) {}, id: "change event handler called")
  +              ..inputHandler = expectAsync((e) {}, id: "input event handler called");
   
             return new async.Future(() {
               var input = dom.document.querySelector("#changeAndInputEvent") as CoreInput;
  
positive.code:         test("validate number", () {
            var template =
                dom.document.querySelector("#validateNumberTemplate") as AutoBindingElement;
            var inputValidCalled = expectAsync(() {}, id: "inputValidCalled");
            var inputInvalidCalled = expectAsync(() {}, id: "inputInvalidCalled");
            var model = template.model = new MyModel()
                ..stringValue = INITIAL_VALUE
                ..inputInvalidHandler = (dom.CustomEvent e) {
                  inputInvalidCalled();
                }
                ..inputValidHandler = (dom.CustomEvent e) {
                  inputValidCalled();
                };
  
            return new async.Future(() {
              var input =
  
negative.code: 
  import "dart:html" as dom;
  import "dart:async" as async;
  
  import "package:polymer/polymer.dart";
  import "package:unittest/unittest.dart";
  