Properly set the exit code for failing tests run directly.

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;
 
@@ skipping 37 matching lines @@
   // In order to run the tests, we set up our own Declarer via
   // [_globalDeclarer], and schedule a microtask to run the tests once they're
   // finished being defined.
   _globalDeclarer = new Declarer();
   scheduleMicrotask(() {
     var suite =
         new Suite(_globalDeclarer.tests,
               path: p.prettyUri(Uri.base),
               platform: "VM")
         .forPlatform(TestPlatform.vm, os: currentOSGuess);
-    // TODO(nweiz): Set the exit code on the VM when issue 6943 is fixed.
-    new NoIoCompactReporter([suite], color: true).run();
+
+    new NoIoCompactReporter([suite], color: true).run().then((success) {
+      // TODO(nweiz): Set the exit code on the VM when issue 6943 is fixed.
+      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.
 ///
 /// The description will be added to the descriptions of any surrounding
 /// [group]s. If [testOn] is passed, it's parsed as a [platform selector][]; the
@@ skipping 99 matching lines @@
 
 /// Handle an error that occurs outside of any test.
 void handleExternalError(error, String message, [stackTrace]) {
   // TODO(nweiz): handle this better.
   registerException(error, stackTrace);
 }
 
 /// Registers an exception that was caught for the current test.
 void registerException(error, [StackTrace stackTrace]) =>
     Invoker.current.handleError(error, stackTrace);