anchor.diff:        });
       });
   
  -    // TODO: transactions seem to be broken - does not send existing value
  -    skip_test('simple value, existing value', () {
  +    test('simple value, existing value', () {
         var testRef = f.child('tx3');
         return testRef.set(42).then((_) {
           return testRef.transaction((curVal) {
  -          expect(curVal, 42);
  -          return 42;
  +          expect(curVal == null || curVal == 42, isTrue);
  +          return 43;
           });
         }).then((result) {
           expect(result.committed, isTrue);
  
positive.code: import 'package:firebase/firebase.dart';
  import 'package:scheduled_test/scheduled_test.dart';
  import 'package:unittest/html_config.dart';
  
negative.code:         var snapshot = result.snapshot;
          expect(snapshot.hasChildren, false);
          expect(snapshot.numChildren, 0);
          expect(snapshot.val(), 43);
        });
      });
    });
  