anchor.diff:            '<template><span>{{x}}</span></template>'));
         testDiv.append(template.createInstance(model, new PolymerExpressions()));
   
  +      var el;
         return new Future(() {
  -        var el = testDiv.query("span");
  +        el = testDiv.query("span");
           expect(el.text, 'abcde');
           expect(model.x, 'abcde');
           model.x = '___';
  -
  -        return new Future(() {
  -          expect(model.x, '___');
  -          expect(el.text, '___');
  -        });
  +      }).then(_nextMicrotask).then((_) {
  +        expect(model.x, '___');
  +        expect(el.text, '___');
         });
       });
   
  
positive.code:         testDiv.append(template.createInstance(model,
              new PolymerExpressions()));
  
          return new Future(() {});
        }, onError: (e) {
          expect('$e', startsWith("Error evaluating expression 'foo':"));
          completer.complete(true);
  
negative.code:         subscription.cancel();
        });
      });
  
  
      test('detects changes to ObservableMap keys/values', () {
        var map = new ObservableMap.from({'a': 1, 'b': 2});
        var template = templateBind(new Element.html('<template>'
            '<template repeat="{{k in x.keys}}">{{k}}:{{x[k]}},</template>'
            '</template>'));
        var model = new NotifyModel(map);
        testDiv.append(template.createInstance(model, new PolymerExpressions()));
  
        return new Future(() {
          expect(testDiv.text, 'a:1,b:2,');
          map.remove('b');
          map['c'] = 3;
        }).then(_nextMicrotask).then((_) {
          expect(testDiv.text, 'a:1,c:3,');
          map['a'] = 4;
        }).then(_nextMicrotask).then((_) {
          expect(testDiv.text, 'a:4,c:3,');
        });
      });
    });
  });
  
  _nextMicrotask(_) => new Future(() {});
  
  @reflectable
  class NotifyModel extends ChangeNotifier {
  