anchor.diff:        "DART_CONFIGURATION='${env['DART_CONFIGURATION']}'",
         "DART_VM_FLAGS='${env['DART_VM_FLAGS']}'",
         ...cmd
  -    ].join(" "));
  -    print([dart, snapshot].join(" "));
  +    ].join(" ").replaceAll('$top/', '').replaceAll('$tmp/', ''));
  +    print([dart, snapshot]
  +        .join(" ")
  +        .replaceAll('$top/', '')
  +        .replaceAll('$tmp/', ''));
     }
   
     String description;
  
positive.code:   String dart;
    String fileName;
    String snapshot;
    Map<String, String> env;
    List<String> cmd;
  }
  
  /// Concrete test runner of bytecode.
  class TestRunnerKBC implements TestRunner {
    TestRunnerKBC(String prefix, String tag, String top, String tmp, this.env,
        this.fileName, List<String> extraFlags, bool kbcSrc) {
      description = '$prefix-$tag';
      dart = '$top/out/$tag/dart';
  
negative.code:   }
  
    void printReproductionCommand() {
      print([dart2js, fileName, '-o', js]
          .join(" ")
          .replaceAll('$top/', '')
          .replaceAll('$tmp/', ''));
      print('nodejs out.js');
    }
  
    String description;
    String dart2js;
    String fileName;
    String js;
    final String top;
    final String tmp;
    Map<String, String> env;
  }
  
  