Make Suite contain a single Group.

test/backend/invoker_test.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:async';
 
 import 'package:fake_async/fake_async.dart';
+import 'package:test/src/backend/group.dart';
 import 'package:test/src/backend/invoker.dart';
 import 'package:test/src/backend/metadata.dart';
 import 'package:test/src/backend/state.dart';
 import 'package:test/src/backend/suite.dart';
 import 'package:test/test.dart';
 
 import '../utils.dart';
 
 void main() {
   var suite;
   setUp(() {
     lastState = null;
-    suite = new Suite([]);
+    suite = new Suite(new Group.root([]));
   });
 
   group("Invoker.current", () {
     var invoker = Invoker.current;
     test("returns null outside of a test body", () {
       expect(invoker, isNull);
     });
 
     test("returns the current invoker in a test body", () async {
       var invoker;
@@ skipping 491 matching lines @@
       expect(liveTest.state.status, equals(Status.complete));
       expect(isComplete, isFalse);
     });
   });
 }
 
 LocalTest _localTest(body(), {Metadata metadata}) {
   if (metadata == null) metadata = new Metadata();
   return new LocalTest("test", metadata, body);
 }