In Array.of and Array.from, fall back to DefineOwnProperty

test/mjsunit/harmony/array-from.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --harmony-arrays
 (function() {
 
 assertEquals(1, Array.from.length);
 
 function assertArrayLikeEquals(value, expected, type) {
@@ skipping 130 matching lines @@
 
 testArrayFrom(Array, Array);
 testArrayFrom(null, Array);
 testArrayFrom({}, Array);
 testArrayFrom(Object, Object);
 testArrayFrom(Other, Other);
 testArrayFrom(Math.cos, Array);
 testArrayFrom(Math.cos.bind(Math), Array);
 testArrayFrom(boundFn, boundFn);
 
+// Assert that [[DefineOwnProperty]] is used in ArrayFrom, meaning a
+// setter isn't called, and a failed [[DefineOwnProperty]] will throw.
+var setterCalled = 0;
+function exotic() {
+  Object.defineProperty(this,  '0', {
+    get: function() { return 2; },
+    set: function() { setterCalled++; }
+  });
+}
+// Check that exotic was defined right

[arv (Not doing code reviews), 2015/06/11 16:41:30]

I would remove this (line  160-165). We have plenty of tests making sure
accessors works correctly ;-)

[Dan Ehrenberg, 2015/06/11 17:25:44]

Done.

+var instance = new exotic();
+assertEquals(2, instance[0]);
+instance[0] = 1;
+assertEquals(2, instance[0]);
+assertEquals(1, setterCalled);
+// Accessor properties can't be overwritten with DefineOwnProperty

[arv (Not doing code reviews), 2015/06/11 16:41:31]

This comment is wrong. The reason why is because you created the property as non
configurable.

[Dan Ehrenberg, 2015/06/11 17:25:44]

Done.

+assertThrows(function () { Array.from.call(exotic, [1]); }, TypeError);
+assertEquals(1, setterCalled);
+
+// Check that array properties defined are writable, enumerable, configurable
+function ordinary() { }
+var x = Array.from.call(ordinary, [2]);
+var xlength = Object.getOwnPropertyDescriptor(x, 'length');
+assertEquals(1, xlength.value);
+assertEquals(true, xlength.writable);
+assertEquals(true, xlength.enumerable);
+assertEquals(true, xlength.configurable);
+var x0 = Object.getOwnPropertyDescriptor(x, 0);
+assertEquals(2, x0.value);
+assertEquals(true, xlength.writable);
+assertEquals(true, xlength.enumerable);
+assertEquals(true, xlength.configurable);
+
 })();