anchor.diff:  
         // Write into the [File].
         generatedFile.writeAsStringSync(htmlFileString);
  -      completer.complete();
       });
  -
  -    return completer.future;
     }
   
     /// Creates the intermediary Dart file that sets the unittest [Configuration].
  
positive.code:   </body>
  </html>
  ''';
  
  
negative.code:   /// [DEFAULT_HTML_TEST_FILE_TEMPLATE_PATH]) will be used to run the browser
    /// test in.
    Future createTestHtmlFile(String testFileName, [String testHtmlFilePath]) {
      return new Future(() {
        if (testHtmlFilePath == null || testHtmlFilePath == "") {
          // If the test does not have an associated test file we'll call the test
          // file inside of a default HTML file.
          return _BROWSER_TEST_DART_FILE_TEMPLATE;
        } else {
          // Custom HTML test files.
          return new File(testHtmlFilePath).readAsString();
        }
      }).then((String htmlFileString) {
        if (testHtmlFilePath == null || testHtmlFilePath == "") {
          htmlFileString =
              htmlFileString.replaceAll("{{test_file_name}}", testFileName);
        } else {
          // For custom HTML test files we add a call to
          // unittest/test_controller.js and we replace the Dart test file call by
          // the intermediary Dart test file that injects the unittest
          // Configuration.
          if (!htmlFileString.contains("packages/unittest/test_controller.js")) {
            htmlFileString = htmlFileString.replaceFirst("</body>",
                '<script type="text/javascript" '
                'src="/packages/unittest/test_controller.js"></script></body>');
          }
        }
  
        // Create the file (and delete it if it already exists).
        String generatedFilePath = '${generatedTestFilesDirectory.path}/' +
            '${testFileName.replaceAll(new RegExp(r'\.dart$'), '.html')}';
        File generatedFile = new File(generatedFilePath);
        if (generatedFile.existsSync()) {
          generatedFile.deleteSync();
  