anchor.diff:  
       test('encoded-space', () {
         expect(HttpServer.bind('localhost', 0).then((server) {
  -        var dir = new Directory('').createTempSync();
  +        var dir = Directory.systemTemp.createTempSync('http_server_virtual_');
           var file = new File('${dir.path}/my file')..createSync();
           var virDir = new VirtualDirectory(dir.path);
   
  
positive.code: 
      test('dir-not-exists', () {
        expect(HttpServer.bind('localhost', 0).then((server) {
          var dir = new Directory('').createTempSync();
          dir.deleteSync();
          var virDir = new VirtualDirectory(dir.path);
  
  
negative.code:     group('in-dir', () {
        test('file-exists', () {
          expect(HttpServer.bind('localhost', 0).then((server) {
            var dir = Directory.systemTemp.createTempSync('http_server_virtual_');
            var dir2 = new Directory('${dir.path}/dir')..createSync();
            var file = new File('${dir2.path}/file')..createSync();
            var virDir = new VirtualDirectory(dir.path);
  