The Tor Browser / file revision

 /* Any copyright is dedicated to the Public Domain.

  * http://creativecommons.org/licenses/publicdomain/  */

 function run_test() {

   const Cc = Components.classes;

   const Ci = Components.interfaces;

   const PREF_NAME = "testPref";

   var ps = Cc["@mozilla.org/preferences-service;1"]

            .getService(Ci.nsIPrefService);

   var prefs = ps.getDefaultBranch(null);

   var userprefs = ps.getBranch(null);

   prefs.setCharPref(PREF_NAME, "test0");

   prefs.lockPref(PREF_NAME);

   do_check_eq("test0", userprefs.getCharPref(PREF_NAME));

   do_check_eq(false, userprefs.prefHasUserValue(PREF_NAME));

   var file = do_get_profile();

   file.append("prefs.js");

   ps.savePrefFile(file);

   prefs.unlockPref(PREF_NAME);

   prefs.setCharPref(PREF_NAME, "test1");

   ps.readUserPrefs(file);

   do_check_eq("test1", userprefs.getCharPref(PREF_NAME));

   do_check_eq(false, userprefs.prefHasUserValue(PREF_NAME));

 }