Expose Zones.

tests/lib/async/zone_run_guarded_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.
+
+import 'package:expect/expect.dart';
+import 'package:async_helper/async_helper.dart';
+import 'dart:async';
+
+main() {
+  Completer done = new Completer();
+  List events = [];
+
+  // runGuarded calls run, captures the synchronous error (if any) and
+  // gives that one to handleUncaughtError.
+
+  Expect.identical(Zone.ROOT, Zone.current);
+  Zone forked;
+  forked = Zone.current.fork(specification: new ZoneSpecification(
+      run: (Zone self, ZoneDelegate parent, Zone origin, f()) {
+        // The zone is still the same as when origin.run was invoked, which
+        // is the root zone. (The origin zone hasn't been set yet).
+        Expect.identical(Zone.ROOT, Zone.current);
+        events.add("forked.run");
+        return parent.run(origin, f);
+      },
+      handleUncaughtError: (Zone self, ZoneDelegate parent, Zone origin, e) {
+        Expect.identical(Zone.ROOT, Zone.current);
+        Expect.identical(forked, origin);
+        events.add("forked.handleUncaught $e");
+        return 499;
+      }));
+
+  var result = forked.runGuarded(() {
+    events.add("runGuarded 1");
+    Expect.identical(forked, Zone.current);
+    return 42;
+  });
+  Expect.identical(Zone.ROOT, Zone.current);
+  Expect.equals(42, result);
+  events.add("after runGuarded 1");
+
+  result = forked.runGuarded(() {
+    events.add("runGuarded 2");
+    Expect.identical(forked, Zone.current);
+    throw 42;
+  });
+  Expect.equals(499, result);
+
+  Expect.listEquals(
+      [ "forked.run", "runGuarded 1", "after runGuarded 1",
+        "forked.run", "runGuarded 2", "forked.handleUncaught 42" ],
+      events);
+
+  events.clear();
+  asyncStart();
+  result = forked.runGuarded(() {
+    Expect.identical(forked, Zone.current);
+    events.add("run closure");
+    runAsync(() {
+      events.add("run closure 2");
+      Expect.identical(forked, Zone.current);
+      done.complete(true);
+      throw 88;
+    });
+    throw 1234;
+  });
+  events.add("after nested runAsync");
+  Expect.equals(499, result);
+
+  done.future.whenComplete(() {
+    Expect.listEquals(
+        ["forked.run", "run closure", "forked.handleUncaught 1234",
+         "after nested runAsync", "forked.run", "run closure 2",
+         "forked.handleUncaught 88" ],
+        events);
+    asyncEnd();
+  });
+}