Stop working around dart-lang/sdk#23497.

lib/src/backend/declarer.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 '../frontend/timeout.dart';
 import '../utils.dart';
 import 'group.dart';
 import 'group_entry.dart';
@@ skipping 60 matching lines @@
 
   /// Defines a test case with the given name and body.
   void test(String name, body(), {String testOn, Timeout timeout, skip,
       Map<String, dynamic> onPlatform, tags}) {
     _checkNotBuilt("test");
 
     var metadata = _metadata.merge(new Metadata.parse(
         testOn: testOn, timeout: timeout, skip: skip, onPlatform: onPlatform,
         tags: tags));
 
-    _entries.add(new LocalTest(_prefix(name), metadata, () {
+    _entries.add(new LocalTest(_prefix(name), metadata, () async {
       // TODO(nweiz): It might be useful to throw an error here if a test starts
       // running while other tests from the same declarer are also running,
       // since they might share closurized state.
 
-      // TODO(nweiz): Use async/await here once issue 23497 has been fixed in
-      // two stable versions.
-      return Invoker.current.waitForOutstandingCallbacks(() {
-        return _runSetUps().then((_) => body());
-      }).then((_) => _runTearDowns());
+      await Invoker.current.waitForOutstandingCallbacks(() async {
+        await _runSetUps();
+        await body();
+      });
+      await _runTearDowns();
     }));
   }
 
   /// Creates a group of tests.
   void group(String name, void body(), {String testOn, Timeout timeout, skip,
       Map<String, dynamic> onPlatform, tags}) {
     _checkNotBuilt("group");
 
     var metadata = _metadata.merge(new Metadata.parse(
         testOn: testOn, timeout: timeout, skip: skip, onPlatform: onPlatform,
@@ skipping 53 matching lines @@
   /// [name] should be the name of the method being called.
   void _checkNotBuilt(String name) {
     if (!_built) return;
     throw new StateError("Can't call $name() once tests have begun running.");
   }
 
   /// Run the set-up functions for this and any parent groups.
   ///
   /// If no set-up functions are declared, this returns a [Future] that
   /// completes immediately.
-  Future _runSetUps() {
-    // TODO(nweiz): Use async/await here once issue 23497 has been fixed in two
-    // stable versions.
-    if (_parent != null) {
-      return _parent._runSetUps().then((_) {
-        return Future.forEach(_setUps, (setUp) => setUp());
-      });
-    }
-
-    return Future.forEach(_setUps, (setUp) => setUp());
+  Future _runSetUps() async {
+    if (_parent != null) await _parent._runSetUps();
+    await Future.forEach(_setUps, (setUp) => setUp());
   }
 
   /// Run the tear-up functions for this and any parent groups.
   ///
   /// If no set-up functions are declared, this returns a [Future] that
   /// completes immediately.
   ///
   /// This should only be called within a test.
   Future _runTearDowns() {
     return Invoker.current.unclosable(() {
@@ skipping 35 matching lines @@
     var completer = new Completer();
 
     Invoker.current.addOutstandingCallback();
     Invoker.current.waitForOutstandingCallbacks(() {
       new Future.sync(body).whenComplete(completer.complete);
     }).then((_) => Invoker.current.removeOutstandingCallback());
 
     return completer.future;
   }
 }