diff -r 000000000000 -r 6474c204b198 services/sync/tests/unit/test_bookmark_batch_fail.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/services/sync/tests/unit/test_bookmark_batch_fail.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,23 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+_("Making sure a failing sync reports a useful error");
+Cu.import("resource://services-sync/engines/bookmarks.js");
+Cu.import("resource://services-sync/service.js");
+
+function run_test() {
+  let engine = new BookmarksEngine(Service);
+  engine._syncStartup = function() {
+    throw "FAIL!";
+  };
+
+  try {
+    _("Try calling the sync that should throw right away");
+    engine._sync();
+    do_throw("Should have failed sync!");
+  }
+  catch(ex) {
+    _("Making sure what we threw ended up as the exception:", ex);
+    do_check_eq(ex, "FAIL!");
+  }
+}