anchor.diff:  
     });
   
  -  group('Dart callback', () {
  +  group('Dart functions', () {
       test('invoke Dart callback from JS', () {
         expect(() => context.callMethod('invokeCallback'), throws);
   
  
positive.code: }
  
  class TestDartObject {}
  
  main() {
    _injectJs();
  
negative.code:     test('return a JS proxy to JavaScript', () {
        var result = context.callMethod('testJsMap', [() => new JsObject.jsify({'value': 42})]);
        expect(result, 42);
      });
  
      test('emulated functions should be callable in JS', () {
        context['callable'] = new Callable();
        var result = context.callMethod('callable');
        expect(result, 'called');
        context.deleteProperty('callable');
      });
  
    });
  