vmservice: basic object graph serialization.

runtime/bin/vmservice/observatory/test/graph_test.dart

+// Copyright (c) 2014, 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 'dart:async';
+import 'package:observatory/object_graph.dart';
+import 'package:observatory/service_io.dart';
+import 'package:unittest/unittest.dart';
+import 'test_helper.dart';
+
+class Foo {
+  Object left;
+  Object right;
+}
+Foo root;
+
+void script() {
+  // Create 3 instances of Foo, with out-degrees 0 (for b), 1 (for a), and 2 (for root).
+  root = new Foo();
+  var a = new Foo();
+  var b = new Foo();
+  root.left = a;
+  root.right = b;
+  a.left = b;
+}
+
+int fooId;
+
+var tests = [
+
+(Isolate isolate) {
+  Completer completer = new Completer();
+  isolate.vm.events.stream.listen((ServiceEvent event) {
+    if (event.eventType == '_Graph') {
+      ReadStream reader = new ReadStream(event.data);
+      ObjectGraph graph = new ObjectGraph(reader);
+      List<ObjectVertex> foos = graph.vertices.where((ObjectVertex obj) => obj.classId == fooId);

[Cutch, 2014/12/02 16:46:26]

assert that fooId != null before?

[koda, 2014/12/02 18:47:12]

Done.

+      expect(foos.length, equals(3));
+      expect(foos.where((ObjectVertex obj) => obj.succ.length == 0).length, equals(1));
+      expect(foos.where((ObjectVertex obj) => obj.succ.length == 1).length, equals(1));
+      expect(foos.where((ObjectVertex obj) => obj.succ.length == 2).length, equals(1));
+      completer.complete();
+    }
+  });
+  return isolate.rootLib.load().then((Library lib) {
+    expect(lib.classes.length, equals(1));
+    // Extract the numerical class id of 'Foo', used in the event listener above.
+    Class fooClass = lib.classes.first;
+    String prefix = "classes/";
+    fooId = int.parse(fooClass.id.substring(prefix.length));

[Cutch, 2014/12/02 16:46:26]

Not necessarily for your change- it might make sense to have a classId getter on
Class.

[koda, 2014/12/02 18:47:12]

Agreed, I've added a TODO.

+    isolate.get('graph');
+    return completer.future;
+  });
+},
+
+];
+
+main(args) => runIsolateTests(args, tests, testeeBefore: script);