Re-land "Extend the mDNS package with a native extension used on Mac OS"

tests/mdns_tests/mdns_tests.dart

-// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2015, the Fletch 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.
+// BSD-style license that can be found in the LICENSE.md file.
 
 import 'dart:async';
 
 import '../../pkg/mdns/test/decode_test.dart' as decode;
 import '../../pkg/mdns/test/lookup_resolver_test.dart' as lookup_resolver;
+import '../../pkg/mdns/test/native_extension_test.dart' as native_extension;
 
-Future<Null> main() async {
-  decode.main();
-  lookup_resolver.main();
+typedef Future NoArgFuture();
+
+Future<Map<String, NoArgFuture>> listTests() async {
+  var tests = <String, NoArgFuture>{};
+  tests['mdns_tests/decode'] = () async => decode.main();
+  tests['mdns_tests/lookup_resolver'] = () async => lookup_resolver.main();
+  tests['mdns_tests/validate_extension'] = native_extension.main;
+  return tests;
 }