anchor.diff:      compiler = createIncrementalCompiler(
           'org-dartlang-test:///a.dart', new HybridFileSystem(fs));
       await rebuild(compiler, outputUri); // this is a full compile.
  -  });
  -
  -  tearDown(() async {
  +  }
  +
  +  tearDown() async {
       outDir.deleteSync(recursive: true);
       lines = null;
  -  });
  +  }
   
     Future<int> computeVmPort() async {
       var portLine = await lines[0];
  -    expect(observatoryPortRegExp.hasMatch(portLine), isTrue);
  +    Expect.isTrue(observatoryPortRegExp.hasMatch(portLine));
       var match = observatoryPortRegExp.firstMatch(portLine);
       return int.parse(match.group(1));
     }
  
positive.code:         new List.generate(expectedLines, (_) => new Completer<String>());
      lines = completers.map((c) => c.future).toList();
      vm.stdout.transform(UTF8.decoder).transform(splitter).listen((line) {
        expect(i, lessThan(expectedLines));
        completers[i++].complete(line);
      }, onDone: () {
        expect(i, expectedLines);
      });
  
      vm.stderr.transform(UTF8.decoder).transform(splitter).toList().then((err) {
        expect(err, isEmpty, reason: err.join('\n'));
      });
  
      programIsDone = vm.exitCode;
  
negative.code:   List<Future<String>> lines;
    Future programIsDone;
  
    String get name;
  
    Future run();
  
    Future test() async {
      await setUp();
      try {
        await run();
        print("$name done");
      } finally {
        await tearDown();
      }
    }
  
    setUp() async {
      outDir = Directory.systemTemp.createTempSync('hotreload_test');
      outputUri = outDir.uri.resolve('test.dill');
      var root = Uri.parse('org-dartlang-test:///');
  