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

test/mjsunit/harmony/array-from.js

Index: test/mjsunit/harmony/array-from.js
diff --git a/test/mjsunit/harmony/array-from.js b/test/mjsunit/harmony/array-from.js
index c294786c46d3ef458edef53d68dececab22fc542..d69dfe24af44853166c9fd049052ca9c1d4c3502 100644
--- a/test/mjsunit/harmony/array-from.js
+++ b/test/mjsunit/harmony/array-from.js
@@ -148,4 +148,37 @@ 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);
+
 })();