Handle Object.observe notifications for setting Array.length

test/mjsunit/harmony/object-observe.js

Index: test/mjsunit/harmony/object-observe.js
diff --git a/test/mjsunit/harmony/object-observe.js b/test/mjsunit/harmony/object-observe.js
index 27cf2f964a2a6c4de76859a765377de8727ec950..188c1bb82e07e326257a2a0daf8565edff58e672 100644
--- a/test/mjsunit/harmony/object-observe.js
+++ b/test/mjsunit/harmony/object-observe.js
@@ -332,3 +332,23 @@ observer.assertCallbackRecords([
   { object: obj, name: "1", type: "deleted", oldValue: 10 },
   { object: obj, name: "1", type: "new" },
 ]);
+
+// Observing array length (including truncation)
+reset();
+var arr = ['a', 'b', 'c', 'd'];
+Object.defineProperty(arr, '0', {configurable: false});
+Object.defineProperty(arr, '2', {get: function(){}});

[rossberg, 2012/11/08 14:26:22]

Perhaps add the case of a non-configurable accessor.

[adamk, 2012/11/08 14:48:01]

Done.

+Object.observe(arr, observer.callback);
+arr.length = 2;
+arr.length = 0;
+arr.length = 10;
+Object.deliverChangeRecords(observer.callback);
+observer.assertCallbackRecords([
+  { object: arr, name: '3', type: 'deleted', oldValue: 'd' },
+  // TODO(adamk): oldValue should not be present below
+  { object: arr, name: '2', type: 'deleted', oldValue: undefined },
+  { object: arr, name: 'length', type: 'updated', oldValue: 4 },
+  { object: arr, name: '1', type: 'deleted', oldValue: 'b' },
+  { object: arr, name: 'length', type: 'updated', oldValue: 2 },
+  { object: arr, name: 'length', type: 'updated', oldValue: 1 },
+]);