anchor.diff:          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 {
  
positive.code:           '<template><span>{{x}}</span></template>'));
        testDiv.append(template.createInstance(model, new PolymerExpressions()));
  
        return new Future(() {
          var el = testDiv.query("span");
          expect(el.text, 'abcde');
          expect(model.x, 'abcde');
          model.x = '___';
  
          return new Future(() {
            expect(model.x, '___');
            expect(el.text, '___');
          });
        });
      });
  
  
negative.code:         testDiv.append(template.createInstance(model,
              new PolymerExpressions()));
  
          return _nextMicrotask(null);
        }, onError: (e) {
          expect('$e', startsWith("Error evaluating expression 'foo':"));
          completer.complete(true);
  