Use the Zone API for registerException.

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 155 matching lines @@
 ///
 /// This function will be called after each test is run. [callback] may be
 /// asynchronous; if so, it must return a [Future].
 ///
 /// If this is called within a test group, it applies only to tests in that
 /// 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]) =>
-    Invoker.current.handleError(error, stackTrace);
+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);
+}