anchor.diff:      if (isDartComponent) {
         group('in a way that the handlers are callable from within the Dart component:', () {
           setUpAll(() {
  -          expect(propsFromDartRender, isNotNull, reason: 'test setup: component must pass props into props.onDartRender');
  +          expect(propsFromDartRender, isNotNull,
  +              reason: 'test setup: component must pass props into props.onDartRender');
           });
   
  -        final dummyEvent = react.SyntheticMouseEvent(null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null);
  -
  -        for (var helper in helpers.where((helper) => helper.isDart)) {
  -          test(helper.description, () {
  -            expect(() => propsFromDartRender[helper.eventPropKey](dummyEvent), returnsNormally);
  +        final dummyEvent = react.SyntheticMouseEvent(null, null, null, null, null, null, null, null, null, null, null,
  +            null, null, null, null, null, null, null, null, null, null, null, null, null, null, null);
  +
  +        for (var eventCase in eventCases.where((helper) => helper.isDart)) {
  +          test(eventCase.description, () {
  +            expect(() => propsFromDartRender[eventCase.eventPropKey](dummyEvent), returnsNormally);
             });
           }
         });
  
positive.code:     });
  
      group('passing Dart events to Dart handlers, and JS events to handlers originating from JS:', () {
        for (var helper in helpers) {
          test(helper.description, () {
            helper.simulate(node);
            expect(events[helper], isNotNull, reason: 'handler should have been called');
            expect(events[helper], helper.isDart ? isA<react.SyntheticMouseEvent>() : isNot(isA<react.SyntheticMouseEvent>()));
          });
        }
      });
  
negative.code: 
  @JS('React.addons.TestUtils.Simulate')
  external dynamic get _Simulate;
  
  void _typedCallbackRefTests<T>(react.ReactComponentFactoryProxy factory) {
    if (T == dynamic) {
  