anchor.diff:  const int MAX_LINE = 80;
   
   class CompactVMConfiguration extends VMConfiguration {
  +  // The VM won't shut down if a receive port is open. Use this to make sure
  +  // we correctly wait for asynchronous tests.
  +  ReceivePort _receivePort;
  +
     DateTime _start;
     int _pass = 0;
     int _fail = 0;
   
     void onInit() {
  +    _receivePort = new ReceivePort();
       // Override and don't call the superclass onInit() to avoid printing the
       // "unittest-suite-..." boilerplate.
     }
  
positive.code:     // Override and don't call the superclass onDone() to avoid printing the
      // "unittest-suite-..." boilerplate.
      Future.wait([stdout.close(), stderr.close()]).then((_) {
        exit(success ? 0 : 1);
      });
    }
  
negative.code: 
  import 'dart:async';
  import 'dart:io';
  import 'dart:isolate';
  
  import 'unittest.dart';
  import 'vm_config.dart';
  