Refactor groups to pipe them through to the runner.

test/utils.dart

Index: test/utils.dart
diff --git a/test/utils.dart b/test/utils.dart
index 5880149aaba33e24b73d15c0eea63f90b2dd8f25..ebcd0c0522f41bd731acec0894f411cdf2b745c4 100644
--- a/test/utils.dart
+++ b/test/utils.dart
@@ -7,6 +7,7 @@ library test.test.utils;
 import 'dart:async';
 import 'dart:collection';
 
+import 'package:test/src/backend/declarer.dart';
 import 'package:test/src/backend/invoker.dart';
 import 'package:test/src/backend/live_test.dart';
 import 'package:test/src/backend/metadata.dart';
@@ -280,3 +281,9 @@ Future expectTestBlocks(test(), stopBlocking(value)) async {
   // completes.
   return future;
 }
+
+/// Runs [body] with a declarer and returns the declared entries.
+List<SuiteEntry> declare(void body()) {
+  var declarer = new Declarer()..declare(body);
+  return declarer.build();
+}