Use package:testing for tools/gardening

tools/gardening/bin/current_summary.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// Collects the test results for all build bots in [buildGroups] for tests
 /// that mention one of the test names given as argument.
 ///
 /// The results are currently pulled from the second to last build since the
 /// last build might not have completed yet.
 
+import 'dart:async';
 import 'dart:math' hide log;
 import 'dart:io';
 
 import 'package:args/args.dart';
 import 'package:gardening/src/bot.dart';
 import 'package:gardening/src/buildbot_data.dart';
 import 'package:gardening/src/buildbot_structures.dart';
 import 'package:gardening/src/util.dart';
 
 void help(ArgParser argParser) {
   print('Displays the current status of specific tests on the buildbot');
   print('The test-names may be fully qualified (such as in ');
   print('"pkg/front_end/test/token_test") or just be a substring of the fully');
   print(' qualified name.');
   print('Usage: current_summary [options] <test-name1> [<test-name2> ...]');
   print('where options are:');
   print(argParser.usage);
 }
 
-main(List<String> args) async {
+Future main(List<String> args) async {
   ArgParser argParser = createArgParser();
   argParser.addOption('group',
       help: "Restricts the build groups\n"
           "to be searched for the results of the given test\n"
           "to those containing the given substring, case insensitive.");
   ArgResults argResults = argParser.parse(args);
   processArgResults(argResults);
 
   Bot bot = new Bot(logdog: argResults['logdog']);
 
@@ skipping 69 matching lines @@
     if (argResults.rest.length == 1) {
       print("Test pattern '${argResults.rest.single}' not found "
           "in any build bot groups.");
     } else {
       print("Test patterns '${argResults.rest.join("', '")}' not found "
           "in any build bot groups.");
     }
   }
   bot.close();
 }