diff -r 000000000000 -r 6474c204b198 js/src/tests/ecma_5/Array/redefine-nonwritable-length-custom-conversion-throw.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/ecma_5/Array/redefine-nonwritable-length-custom-conversion-throw.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,58 @@
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ * Contributor:
+ *   Jeff Walden <jwalden+code@mit.edu>
+ */
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 866700;
+var summary = "Assertion redefining non-writable length to a non-numeric value";
+
+print(BUGNUMBER + ": " + summary);
+
+/**************
+ * BEGIN TEST *
+ **************/
+
+var count = 0;
+
+var convertible =
+  {
+    valueOf: function()
+    {
+      count++;
+      if (count > 2)
+        return 0;
+      throw new SyntaxError("fnord");
+    }
+  };
+
+var arr = [];
+Object.defineProperty(arr, "length", { value: 0, writable: false });
+
+try
+{
+  Object.defineProperty(arr, "length",
+                        {
+                          value: convertible,
+                          writable: true,
+                          configurable: true,
+                          enumerable: true
+                        });
+  throw new Error("didn't throw");
+}
+catch (e)
+{
+  assertEq(e instanceof SyntaxError, true, "expected SyntaxError, got " + e);
+}
+
+assertEq(count, 1);
+assertEq(arr.length, 0);
+
+/******************************************************************************/
+
+if (typeof reportCompare === "function")
+  reportCompare(true, true);
+
+print("Tests complete");