anchor.diff:        ? _name
         : "${parent.fullName}$groupSep$_name";
   
  -  GroupContext([this.parent, this._name = '']) {
  +  _GroupContext([this.parent, this._name = '']) {
       _testSetup = parentSetup;
       _testTeardown = parentTeardown;
     }
  
positive.code:  * Setup and teardown functions for a group and its parents, the latter
   * for chaining.
   */
  class GroupContext {
    final GroupContext parent;
  
    /** Description text of the current test group. */
    final String _name;
  
negative.code: // We use a 'dummy' context for the top level to eliminate null
  // checks when querying the context. This allows us to easily
  //  support top-level setUp/tearDown functions as well.
  final _rootContext = new _GroupContext();
  _GroupContext _currentContext = _rootContext;
  
  int _currentTestCaseIndex = 0;
  
  