implement dirty checking for @observable objects

pkg/observe/test/list_change_test.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.
 
+import 'dart:async';
 import 'package:observe/observe.dart';
 import 'package:unittest/unittest.dart';
-import 'utils.dart';
+import 'observe_test_utils.dart';
 
 // This file contains code ported from:
 // https://github.com/rafaelw/ChangeSummary/blob/master/tests/test.js
 
 main() {
   // TODO(jmesserly): rename this? Is summarizeListChanges coming back?
   group('summarizeListChanges', listChangeTests);
 }
 
 // TODO(jmesserly): port or write array fuzzer tests
 listChangeTests() {
+  StreamSubscription sub;
 
-  test('sequential adds', () {
+  tearDown(() { sub.cancel(); });
+
+  observeTest('sequential adds', () {
     var model = toObservable([]);
     model.add(0);
 
     var summary;
-    var sub = model.changes.listen((r) { summary = _filter(r); });
+    sub = model.changes.listen((r) { summary = _filter(r); });
 
     model.add(1);
     model.add(2);
 
     expect(summary, null);
-    deliverChangeRecords();
+    performMicrotaskCheckpoint();
 
     expectChanges(summary, [_delta(1, 0, 2)]);
   });
 
-  test('List Splice Truncate And Expand With Length', () {
+  observeTest('List Splice Truncate And Expand With Length', () {
     var model = toObservable(['a', 'b', 'c', 'd', 'e']);
 
     var summary;
-    var sub = model.changes.listen((r) { summary = _filter(r); });
+    sub = model.changes.listen((r) { summary = _filter(r); });
 
     model.length = 2;
 
-    deliverChangeRecords();
+    performMicrotaskCheckpoint();
     expectChanges(summary, [_delta(2, 3, 0)]);
     summary = null;
 
     model.length = 5;
 
-    deliverChangeRecords();
+    performMicrotaskCheckpoint();
     expectChanges(summary, [_delta(2, 0, 3)]);
   });
 
   group('List deltas can be applied', () {
 
     var summary = null;
 
     observeArray(model) {
-      model.changes.listen((records) { summary = _filter(records); });
+      sub = model.changes.listen((records) { summary = _filter(records); });
     }
 
     applyAndCheckDeltas(model, copy) {
       summary = null;
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
 
       // apply deltas to the copy
       for (var delta in summary) {
         copy.removeRange(delta.index, delta.index + delta.removedCount);
         for (int i = delta.addedCount - 1; i >= 0; i--) {
           copy.insert(delta.index, model[delta.index + i]);
         }
       }
 
       // Note: compare strings for easier debugging.
       expect('$copy', '$model', reason: '!!! summary $summary');
     }
 
-    test('Contained', () {
+    observeTest('Contained', () {
       var model = toObservable(['a', 'b']);
       var copy = model.toList();
       observeArray(model);
 
       model.removeAt(1);
       model.insertAll(0, ['c', 'd', 'e']);
       model.removeRange(1, 3);
       model.insert(1, 'f');
 
       applyAndCheckDeltas(model, copy);
     });
 
-    test('Delete Empty', () {
+    observeTest('Delete Empty', () {
       var model = toObservable([1]);
       var copy = model.toList();
       observeArray(model);
 
       model.removeAt(0);
       model.insertAll(0, ['a', 'b', 'c']);
 
       applyAndCheckDeltas(model, copy);
     });
 
-    test('Right Non Overlap', () {
+    observeTest('Right Non Overlap', () {
       var model = toObservable(['a', 'b', 'c', 'd']);
       var copy = model.toList();
       observeArray(model);
 
       model.removeRange(0, 1);
       model.insert(0, 'e');
       model.removeRange(2, 3);
       model.insertAll(2, ['f', 'g']);
 
       applyAndCheckDeltas(model, copy);
     });
 
-    test('Left Non Overlap', () {
+    observeTest('Left Non Overlap', () {
       var model = toObservable(['a', 'b', 'c', 'd']);
       var copy = model.toList();
       observeArray(model);
 
       model.removeRange(3, 4);
       model.insertAll(3, ['f', 'g']);
       model.removeRange(0, 1);
       model.insert(0, 'e');
 
       applyAndCheckDeltas(model, copy);
     });
 
-    test('Right Adjacent', () {
+    observeTest('Right Adjacent', () {
       var model = toObservable(['a', 'b', 'c', 'd']);
       var copy = model.toList();
       observeArray(model);
 
       model.removeRange(1, 2);
       model.insert(3, 'e');
       model.removeRange(2, 3);
       model.insertAll(0, ['f', 'g']);
 
       applyAndCheckDeltas(model, copy);
     });
 
-    test('Left Adjacent', () {
+    observeTest('Left Adjacent', () {
       var model = toObservable(['a', 'b', 'c', 'd']);
       var copy = model.toList();
       observeArray(model);
 
       model.removeRange(2, 4);
       model.insert(2, 'e');
 
       model.removeAt(1);
       model.insertAll(1, ['f', 'g']);
 
       applyAndCheckDeltas(model, copy);
     });
 
-    test('Right Overlap', () {
+    observeTest('Right Overlap', () {
       var model = toObservable(['a', 'b', 'c', 'd']);
       var copy = model.toList();
       observeArray(model);
 
       model.removeAt(1);
       model.insert(1, 'e');
       model.removeAt(1);
       model.insertAll(1, ['f', 'g']);
 
       applyAndCheckDeltas(model, copy);
     });
 
-    test('Left Overlap', () {
+    observeTest('Left Overlap', () {
       var model = toObservable(['a', 'b', 'c', 'd']);
       var copy = model.toList();
       observeArray(model);
 
       model.removeAt(2);
       model.insertAll(2, ['e', 'f', 'g']);
       // a b [e f g] d
       model.removeRange(1, 3);
       model.insertAll(1, ['h', 'i', 'j']);
       // a [h i j] f g d
 
       applyAndCheckDeltas(model, copy);
     });
 
-    test('Prefix And Suffix One In', () {
+    observeTest('Prefix And Suffix One In', () {
       var model = toObservable(['a', 'b', 'c', 'd']);
       var copy = model.toList();
       observeArray(model);
 
       model.insert(0, 'z');
       model.add('z');
 
       applyAndCheckDeltas(model, copy);
     });
 
-    test('Remove First', () {
+    observeTest('Remove First', () {
       var model = toObservable([16, 15, 15]);
       var copy = model.toList();
       observeArray(model);
 
       model.removeAt(0);
 
       applyAndCheckDeltas(model, copy);
     });
 
-    test('Update Remove', () {
+    observeTest('Update Remove', () {
       var model = toObservable(['a', 'b', 'c', 'd']);
       var copy = model.toList();
       observeArray(model);
 
       model.removeAt(2);
       model.insertAll(2, ['e', 'f', 'g']);  // a b [e f g] d
       model[0] = 'h';
       model.removeAt(1);
 
       applyAndCheckDeltas(model, copy);
     });
 
-    test('Remove Mid List', () {
+    observeTest('Remove Mid List', () {
       var model = toObservable(['a', 'b', 'c', 'd']);
       var copy = model.toList();
       observeArray(model);
 
       model.removeAt(2);
 
       applyAndCheckDeltas(model, copy);
     });
   });
 
   group('edit distance', () {
     var summary = null;
 
     observeArray(model) {
-      model.changes.listen((records) { summary = _filter(records); });
+      sub = model.changes.listen((records) { summary = _filter(records); });
     }
 
     assertEditDistance(orig, expectDistance) {
       summary = null;
-      deliverChangeRecords();
+      performMicrotaskCheckpoint();
       var actualDistance = 0;
 
       if (summary != null) {
         for (var delta in summary) {
           actualDistance += delta.addedCount + delta.removedCount;
         }
       }
 
       expect(actualDistance, expectDistance);
     }
 
-    test('add items', () {
+    observeTest('add items', () {
       var model = toObservable([]);
       observeArray(model);
       model.addAll([1, 2, 3]);
       assertEditDistance(model, 3);
     });
 
-    test('trunacte and add, sharing a contiguous block', () {
+    observeTest('trunacte and add, sharing a contiguous block', () {
       var model = toObservable(['x', 'x', 'x', 'x', '1', '2', '3']);
       observeArray(model);
       model.length = 0;
       model.addAll(['1', '2', '3', 'y', 'y', 'y', 'y']);
       // Note: unlike the JS implementation, we don't perform a full diff.
       // The change records are computed with no regards to the *contents* of
       // the array. Thus, we get 14 instead of 8.
       assertEditDistance(model, 14);
     });
 
-    test('truncate and add, sharing a discontiguous block', () {
+    observeTest('truncate and add, sharing a discontiguous block', () {
       var model = toObservable(['1', '2', '3', '4', '5']);
       observeArray(model);
       model.length = 0;
       model.addAll(['a', '2', 'y', 'y', '4', '5', 'z', 'z']);
       // Note: unlike the JS implementation, we don't perform a full diff.
       // The change records are computed with no regards to the *contents* of
       // the array. Thus, we get 13 instead of 7.
       assertEditDistance(model, 13);
     });
 
-    test('insert at beginning and end', () {
+    observeTest('insert at beginning and end', () {
       var model = toObservable([2, 3, 4]);
       observeArray(model);
       model.insert(0, 5);
       model[2] = 6;
       model.add(7);
       assertEditDistance(model, 4);
     });
   });
 }
 
 _delta(i, r, a) => new ListChangeRecord(i, removedCount: r, addedCount: a);
 _filter(records) => records.where((r) => r is ListChangeRecord).toList();