Allow Suites to be added to an Engine over time.

lib/test.dart

 // Copyright (c) 2013, 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.
 
 library test;
 
 import 'dart:async';
 
 import 'package:path/path.dart' as p;
 
 import 'src/backend/declarer.dart';
 import 'src/backend/suite.dart';
 import 'src/backend/test_platform.dart';
 import 'src/frontend/timeout.dart';
+import 'src/runner/engine.dart';
 import 'src/runner/reporter/expanded.dart';
 import 'src/utils.dart';
 
 export 'package:matcher/matcher.dart';
 
 export 'src/frontend/expect.dart';
 export 'src/frontend/expect_async.dart';
 export 'src/frontend/future_matchers.dart';
 export 'src/frontend/on_platform.dart';
 export 'src/frontend/prints_matcher.dart';
@@ skipping 23 matching lines @@
   // [_globalDeclarer], and schedule a microtask to run the tests once they're
   // finished being defined.
   _globalDeclarer = new Declarer();
   scheduleMicrotask(() async {
     var suite =
         new Suite(_globalDeclarer.tests,
               path: p.prettyUri(Uri.base),
               platform: "VM")
         .forPlatform(TestPlatform.vm, os: currentOSGuess);
 
-    var success = await new ExpandedReporter([suite], color: true).run();
+    var engine = new Engine();
+    engine.suiteSink.add(suite);
+    engine.suiteSink.close();
+    ExpandedReporter.watch(engine,
+        color: true, printPath: false, printPlatform: false);
+
+    var success = await engine.run();
     // TODO(nweiz): Set the exit code on the VM when issue 6943 is fixed.
-    // TODO(nweiz): Just "return;" when issue 23200 is fixed.
-    if (success) return null;
+    if (success) return;
     print('');
     new Future.error("Dummy exception to set exit code.");
   });
   return _globalDeclarer;
 }
 
 // TODO(nweiz): This and other top-level functions should throw exceptions if
 // they're called after the declarer has finished declaring.
 /// Creates a new test case with the given description and body.
 ///
@@ skipping 98 matching lines @@
 /// group. [callback] will be run before any tear-down callbacks in parent
 /// groups or at the top level.
 void tearDown(callback()) => _declarer.tearDown(callback);
 
 /// Registers an exception that was caught for the current test.
 void registerException(error, [StackTrace stackTrace]) {
   // This will usually forward directly to [Invoker.current.handleError], but
   // going through the zone API allows other zones to consistently see errors.
   Zone.current.handleUncaughtError(error, stackTrace);
 }