implement dirty checking for @observable objects

pkg/mdv/test/mdv_test_utils.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.
+
+library observe_utils;
+
+import 'dart:async';
+import 'package:observe/observe.dart';
+import 'package:unittest/unittest.dart';
+
+toSymbolMap(Map map) {
+  var result = new ObservableMap.linked();
+  map.forEach((key, value) {
+    if (value is Map) value = toSymbolMap(value);
+    result[new Symbol(key)] = value;
+  });
+  return result;
+}
+
+class FooBarModel extends ObservableBase {
+  @observable var foo;
+  @observable var bar;
+
+  FooBarModel([this.foo, this.bar]);
+}
+
+class FooBarNotifyModel extends ChangeNotifierBase implements FooBarModel {
+  var _foo;
+  var _bar;
+
+  FooBarNotifyModel([this._foo, this._bar]);
+
+  get foo => _foo;
+  set foo(value) {
+    _foo = notifyPropertyChange(const Symbol('foo'), _foo, value);
+  }
+
+  get bar => _bar;
+  set bar(value) {
+    _bar = notifyPropertyChange(const Symbol('bar'), _bar, value);
+  }
+}
+
+// TODO(jmesserly): this is a copy/paste from observe_test_utils.dart
+// Is it worth putting it in its own package, or in an existing one?
+
+void performMicrotaskCheckpoint() {
+  Observable.dirtyCheck();
+
+  while (_pending.length > 0) {
+    var pending = _pending;
+    _pending = [];
+
+    for (var callback in pending) {
+      try {
+        callback();
+      } catch (e, s) {
+        new Completer().completeError(e, s);
+      }
+    }
+
+    Observable.dirtyCheck();
+  }
+}
+
+List<Function> _pending = [];
+
+wrapMicrotask(void testCase()) {
+  return () {
+    runZonedExperimental(() {
+      try {
+        testCase();
+      } finally {
+        performMicrotaskCheckpoint();
+      }
+    }, onRunAsync: (callback) => _pending.add(callback));
+  };
+}
+
+observeTest(name, testCase) => test(name, wrapMicrotask(testCase));
+
+solo_observeTest(name, testCase) => solo_test(name, wrapMicrotask(testCase));