--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/test/script/basic/es6/JDK-8151809.js	Mon Mar 21 11:50:23 2016 +0100
@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ * 
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ * 
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ * 
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ * 
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * JDK-8151809: ES6 Map/Set insertion with existing keys changes iteration order
+ *
+ * @test
+ * @run
+ * @option --language=es6
+ */
+
+function assertSetIteratorResult(result, expectedDone, expectedValue) {
+    Assert.assertEquals(result.done, expectedDone);
+    Assert.assertEquals(result.value, expectedValue);
+}
+
+function assertMapIteratorResult(result, expectedDone, expectedKey, expectedValue) {
+    Assert.assertEquals(result.done, expectedDone);
+    if (expectedDone) {
+        Assert.assertEquals(result.value, undefined);
+    } else {
+        Assert.assertEquals(result.value[0], expectedKey);
+        Assert.assertEquals(result.value[1], expectedValue);
+    }
+}
+
+let set = new Set(["foo", "bar", "foo"]);
+let iter = set[Symbol.iterator]();
+assertSetIteratorResult(iter.next(), false, "foo");
+assertSetIteratorResult(iter.next(), false, "bar");
+assertSetIteratorResult(iter.next(), true);
+
+set.add ("foo");
+iter = set[Symbol.iterator]();
+assertSetIteratorResult(iter.next(), false, "foo", false);
+assertSetIteratorResult(iter.next(), false, "bar", false);
+assertSetIteratorResult(iter.next(), true);
+
+set.delete("foo");
+set.add ("foo");
+assertSetIteratorResult(iter.next(), true);
+iter = set[Symbol.iterator]();
+assertSetIteratorResult(iter.next(), false, "bar", false);
+assertSetIteratorResult(iter.next(), false, "foo", false);
+assertSetIteratorResult(iter.next(), true);
+
+
+let map = new Map([["foo", 1], ["bar", 2], ["foo", 3]]);
+iter = map[Symbol.iterator]();
+assertMapIteratorResult(iter.next(), false, "foo", 3);
+assertMapIteratorResult(iter.next(), false, "bar", 2);
+assertMapIteratorResult(iter.next(), true);
+
+
+map.set("foo", 4);
+iter = map[Symbol.iterator]();
+assertMapIteratorResult(iter.next(), false, "foo", 4);
+assertMapIteratorResult(iter.next(), false, "bar", 2);
+assertMapIteratorResult(iter.next(), true);
+
+map.delete("foo");
+map.set("foo", 5);
+assertMapIteratorResult(iter.next(), true);
+iter = map[Symbol.iterator]();
+assertMapIteratorResult(iter.next(), false, "bar", 2);
+assertMapIteratorResult(iter.next(), false, "foo", 5);
+assertMapIteratorResult(iter.next(), true);