The Tor Browser / file revision

 const Ci = Components.interfaces;

 const Cc = Components.classes;

 const CWD = do_get_cwd();

 function checkOS(os) {

   const nsILocalFile_ = "nsILocalFile" + os;

   return nsILocalFile_ in Components.interfaces &&

          CWD instanceof Components.interfaces[nsILocalFile_];

 }

 const isWin = checkOS("Win");

 function run_test() {

   var envVar = isWin ? "USERPROFILE" : "HOME";

   var dirSvc = Cc["@mozilla.org/file/directory_service;1"].getService(Ci.nsIProperties);

   var homeDir = dirSvc.get("Home", Ci.nsIFile);

   var env = Cc["@mozilla.org/process/environment;1"].getService(Ci.nsIEnvironment);

   var expected = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsILocalFile);

   expected.initWithPath(env.get(envVar));

   do_check_eq(homeDir.path, expected.path);

 }