diff -r 000000000000 -r 6474c204b198 services/common/tests/unit/test_utils_utf8.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/services/common/tests/unit/test_utils_utf8.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,11 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+Cu.import("resource://services-common/utils.js");
+
+function run_test() {
+  let str = "Umlaute: \u00FC \u00E4\n"; // Umlaute: ü ä
+  let encoded = CommonUtils.encodeUTF8(str);
+  let decoded = CommonUtils.decodeUTF8(encoded);
+  do_check_eq(decoded, str);
+}