diff -r 000000000000 -r 6474c204b198 js/xpconnect/tests/unit/test_bug677864.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/xpconnect/tests/unit/test_bug677864.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,11 @@
+function check_cl(iface, desc) {
+    do_check_eq(iface.QueryInterface(Components.interfaces.nsIClassInfo).classDescription, desc);
+}
+
+function run_test() {
+    check_cl(Components.interfaces, 'XPCComponents_Interfaces');
+    check_cl(Components.interfacesByID, 'XPCComponents_InterfacesByID');
+    check_cl(Components.classes, 'XPCComponents_Classes');
+    check_cl(Components.classesByID, 'XPCComponents_ClassesByID');
+    check_cl(Components.results, 'XPCComponents_Results');
+}