implement dirty checking for @observable objects

pkg/observe/test/observable_list_test.dart

Index: pkg/observe/test/observable_list_test.dart
diff --git a/pkg/observe/test/observable_list_test.dart b/pkg/observe/test/observable_list_test.dart
index b886f039aafb9c82f53ddb8e38e5a0ea60c54d7b..60ddadd5368a5260b8fa82bced655f9bc680db29 100644
--- a/pkg/observe/test/observable_list_test.dart
+++ b/pkg/observe/test/observable_list_test.dart
@@ -2,15 +2,20 @@
 // 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:observe/observe.dart';
 import 'package:unittest/unittest.dart';
-import 'utils.dart';
+import 'observe_test_utils.dart';
 
 main() {
   // TODO(jmesserly): need all standard List API tests.
 
   const _LENGTH = const Symbol('length');
 
+  StreamSubscription sub;
+
+  sharedTearDown() { sub.cancel(); }
+
   group('observe length', () {
 
     ObservableList list;
@@ -19,53 +24,54 @@ main() {
     setUp(() {
       list = toObservable([1, 2, 3]);
       changes = null;
-      list.changes.listen((records) {
+      sub = list.changes.listen((records) {
         changes = records.where((r) => r.changes(_LENGTH)).toList();
       });
     });
 
-    test('add changes length', () {
+    tearDown(sharedTearDown);
+
+    observeTest('add changes length', () {
       list.add(4);
       expect(list, [1, 2, 3, 4]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, [_lengthChange]);
     });
 
-    test('removeObject', () {
+    observeTest('removeObject', () {
       list.remove(2);
       expect(list, orderedEquals([1, 3]));
 
-      deliverChangeRecords();
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, [_lengthChange]);
     });
 
-    test('removeRange changes length', () {
+    observeTest('removeRange changes length', () {
       list.add(4);
       list.removeRange(1, 3);
       expect(list, [1, 4]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, [_lengthChange]);
     });
 
-    test('length= changes length', () {
+    observeTest('length= changes length', () {
       list.length = 5;
       expect(list, [1, 2, 3, null, null]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, [_lengthChange]);
     });
 
-    test('[]= does not change length', () {
+    observeTest('[]= does not change length', () {
       list[2] = 9000;
       expect(list, [1, 2, 9000]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, []);
     });
 
-    test('clear changes length', () {
+    observeTest('clear changes length', () {
       list.clear();
       expect(list, []);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, [_lengthChange]);
     });
   });
@@ -77,78 +83,80 @@ main() {
     setUp(() {
       list = toObservable([1, 2, 3]);
       changes = null;
-      list.changes.listen((records) {
+      sub = list.changes.listen((records) {
         changes = records.where((r) => r.changes(1)).toList();
       });
     });
 
-    test('add does not change existing items', () {
+    tearDown(sharedTearDown);
+
+    observeTest('add does not change existing items', () {
       list.add(4);
       expect(list, [1, 2, 3, 4]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, []);
     });
 
-    test('[]= changes item', () {
+    observeTest('[]= changes item', () {
       list[1] = 777;
       expect(list, [1, 777, 3]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, [_change(1, addedCount: 1, removedCount: 1)]);
     });
 
-    test('[]= on a different item does not fire change', () {
+    observeTest('[]= on a different item does not fire change', () {
       list[2] = 9000;
       expect(list, [1, 2, 9000]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, []);
     });
 
-    test('set multiple times results in one change', () {
+    observeTest('set multiple times results in one change', () {
       list[1] = 777;
       list[1] = 42;
       expect(list, [1, 42, 3]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, [
         _change(1, addedCount: 1, removedCount: 1),
       ]);
     });
 
-    test('set length without truncating item means no change', () {
+    observeTest('set length without truncating item means no change', () {
       list.length = 2;
       expect(list, [1, 2]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, []);
     });
 
-    test('truncate removes item', () {
+    observeTest('truncate removes item', () {
       list.length = 1;
       expect(list, [1]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, [_change(1, removedCount: 2)]);
     });
 
-    test('truncate and add new item', () {
+    observeTest('truncate and add new item', () {
       list.length = 1;
       list.add(42);
       expect(list, [1, 42]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, [
         _change(1, removedCount: 2, addedCount: 1)
       ]);
     });
 
-    test('truncate and add same item', () {
+    observeTest('truncate and add same item', () {
       list.length = 1;
       list.add(2);
       expect(list, [1, 2]);
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(changes, [
         _change(1, removedCount: 2, addedCount: 1)
       ]);
     });
   });
 
-  test('toString', () {
+  observeTest('toString', () {
     var list = toObservable([1, 2, 3]);
     expect(list.toString(), '[1, 2, 3]');
   });
@@ -161,10 +169,12 @@ main() {
     setUp(() {
       list = toObservable([1, 2, 3, 1, 3, 4]);
       records = null;
-      list.changes.listen((r) { records = r; });
+      sub = list.changes.listen((r) { records = r; });
     });
 
-    test('read operations', () {
+    tearDown(sharedTearDown);
+
+    observeTest('read operations', () {
       expect(list.length, 6);
       expect(list[0], 1);
       expect(list.indexOf(4), 5);
@@ -175,69 +185,69 @@ main() {
       var copy = new List<int>();
       list.forEach((i) { copy.add(i); });
       expect(copy, orderedEquals([1, 2, 3, 1, 3, 4]));
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
 
       // no change from read-only operators
       expectChanges(records, null);
     });
 
-    test('add', () {
+    observeTest('add', () {
       list.add(5);
       list.add(6);
       expect(list, orderedEquals([1, 2, 3, 1, 3, 4, 5, 6]));
 
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(records, [
         _lengthChange,
         _change(6, addedCount: 2)
       ]);
     });
 
-    test('[]=', () {
+    observeTest('[]=', () {
       list[1] = list.last;
       expect(list, orderedEquals([1, 4, 3, 1, 3, 4]));
 
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(records, [ _change(1, addedCount: 1, removedCount: 1) ]);
     });
 
-    test('removeLast', () {
+    observeTest('removeLast', () {
       expect(list.removeLast(), 4);
       expect(list, orderedEquals([1, 2, 3, 1, 3]));
 
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(records, [
         _lengthChange,
         _change(5, removedCount: 1)
       ]);
     });
 
-    test('removeRange', () {
+    observeTest('removeRange', () {
       list.removeRange(1, 4);
       expect(list, orderedEquals([1, 3, 4]));
 
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(records, [
         _lengthChange,
         _change(1, removedCount: 3),
       ]);
     });
 
-    test('sort', () {
+    observeTest('sort', () {
       list.sort((x, y) => x - y);
       expect(list, orderedEquals([1, 1, 2, 3, 3, 4]));
 
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(records, [
         _change(1, addedCount: 5, removedCount: 5),
       ]);
     });
 
-    test('clear', () {
+    observeTest('clear', () {
       list.clear();
       expect(list, []);
 
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       expectChanges(records, [
         _lengthChange,
         _change(0, removedCount: 6)