diff -r 000000000000 -r 6474c204b198 dom/indexedDB/test/unit/test_unique_index_update.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/indexedDB/test/unit/test_unique_index_update.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,64 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+var testGenerator = testSteps();
+
+function testSteps()
+{
+  let request = indexedDB.open(this.window ? window.location.pathname : "Splendid Test", 1);
+  request.onerror = errorHandler;
+  request.onupgradeneeded = grabEventAndContinueHandler;
+  request.onsuccess = grabEventAndContinueHandler;
+
+  let event = yield undefined;
+
+  let db = event.target.result;
+
+  for each (let autoIncrement in [false, true]) {
+    let objectStore =
+      db.createObjectStore(autoIncrement, { keyPath: "id",
+                                            autoIncrement: autoIncrement });
+    objectStore.createIndex("", "index", { unique: true });
+
+    for (let i = 0; i < 10; i++) {
+      objectStore.add({ id: i, index: i });
+    }
+  }
+
+  event = yield undefined;
+  is(event.type, "success", "expect a success event");
+
+  for each (let autoIncrement in [false, true]) {
+    objectStore = db.transaction(autoIncrement, "readwrite")
+                    .objectStore(autoIncrement);
+
+    request = objectStore.put({ id: 5, index: 6 });
+    request.onsuccess = unexpectedSuccessHandler;
+    request.addEventListener("error", new ExpectError("ConstraintError", true));
+    event = yield undefined;
+
+    event.preventDefault();
+
+    let keyRange = IDBKeyRange.only(5);
+
+    objectStore.index("").openCursor(keyRange).onsuccess = function(event) {
+      let cursor = event.target.result;
+      ok(cursor, "Must have a cursor here");
+
+      is(cursor.value.index, 5, "Still have the right index value");
+
+      cursor.value.index = 6;
+
+      request = cursor.update(cursor.value);
+      request.onsuccess = unexpectedSuccessHandler;
+      request.addEventListener("error", new ExpectError("ConstraintError", true));
+    };
+
+    yield undefined;
+  }
+
+  finishTest();
+  yield undefined;
+}