Migrate async tests to strong

tests/lib_strong/async/zone_empty_description_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';
+
+testForkedZone(Zone forked) {
+  var result;
+  result = forked.run(() {
+    Expect.identical(forked, Zone.current);
+    return 499;
+  });
+  Expect.equals(499, result);
+  Expect.identical(Zone.ROOT, Zone.current);
+
+  result = forked.runUnary((x) {
+    Expect.equals(42, x);
+    Expect.identical(forked, Zone.current);
+    return -499;
+  }, 42);
+  Expect.equals(-499, result);
+  Expect.identical(Zone.ROOT, Zone.current);
+
+  bool runGuardedDidRun = false;
+  forked.runGuarded(() {
+    runGuardedDidRun = true;
+    Expect.identical(forked, Zone.current);
+  });
+  Expect.identical(Zone.ROOT, Zone.current);
+  Expect.isTrue(runGuardedDidRun);
+
+  runGuardedDidRun = false;
+  forked.runUnaryGuarded((x) {
+    runGuardedDidRun = true;
+    Expect.equals(42, x);
+    Expect.identical(forked, Zone.current);
+  }, 42);
+  Expect.identical(Zone.ROOT, Zone.current);
+  Expect.isTrue(runGuardedDidRun);
+
+  var callback = () => 499;
+  Expect.identical(callback, forked.registerCallback(callback));
+  Expect.identical(Zone.ROOT, Zone.current);
+
+  var callback1 = (x) => 42 + x;
+  Expect.identical(callback1, forked.registerUnaryCallback(callback1));
+  Expect.identical(Zone.ROOT, Zone.current);
+
+  asyncStart();
+  bool asyncDidRun = false;
+  forked.scheduleMicrotask(() {
+    Expect.identical(forked, Zone.current);
+    asyncDidRun = true;
+    asyncEnd();
+  });
+  Expect.isFalse(asyncDidRun);
+  Expect.identical(Zone.ROOT, Zone.current);
+
+  asyncStart();
+  bool timerDidRun = false;
+  forked.createTimer(const Duration(milliseconds: 0), () {
+    Expect.identical(forked, Zone.current);
+    timerDidRun = true;
+    asyncEnd();
+  });
+  Expect.identical(Zone.ROOT, Zone.current);
+}
+
+main() {
+  Expect.identical(Zone.ROOT, Zone.current);
+  Zone forked = Zone.current.fork();
+  Expect.isFalse(identical(Zone.ROOT, forked));
+  testForkedZone(forked);
+  Zone forkedChild = forked.fork();
+  testForkedZone(forkedChild);
+}