Add _getPorts rpc test

runtime/observatory/tests/service/get_ports_rpc_test.dart

+// Copyright (c) 2015, 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.
+// VMOptions=--compile-all --error_on_bad_type --error_on_bad_override
+
+library get_ports_rpc_test;
+
+import 'dart:async';
+import 'dart:isolate';
+import 'package:observatory/service_io.dart';
+import 'package:unittest/unittest.dart';
+
+import 'test_helper.dart';
+
+var port1;
+var port2;
+
+void warmup() {
+  port1 = new RawReceivePort(null);
+  port2 = new RawReceivePort((_) {
+  });
+}
+
+int countHandlerMatches(ports, matcher) {
+  var matches = 0;
+  for (var port in ports) {
+    if (matcher(port['handler'])) {
+      matches++;
+    }
+  }
+  return matches;
+}
+
+bool nullMatcher(handler) {
+  return handler.isNull;
+}
+
+bool closureMatcher(handler) {
+  return handler.isClosure;
+}
+
+var tests = [
+  (Isolate isolate) async {
+    var result = await isolate.invokeRpc('_getPorts', {});
+    expect(result['type'], equals('_Ports'));
+    expect(result['ports'], isList);
+    var ports = result['ports'];
+    // There are three ports: the two created in warmup and the stdin listener
+    // created by the test harness.
+    expect(ports.length, equals(3));
+    expect(countHandlerMatches(ports, nullMatcher), equals(1));
+    expect(countHandlerMatches(ports, closureMatcher), equals(2));
+  },
+];
+
+main(args) async => runIsolateTests(args, tests, testeeBefore:warmup);