add: if (parentDir.exists()) parentDir.remove(true); 
context: function test_backup_new_folder(){  var msc = getOpenedDatabase();  var parentDir = getTestDB().parent;  parentDir.append("test_storage_temp");  parentDir.create(Ci.nsIFile.DIRECTORY_TYPE, 0755);  do_check_true(parentDir.exists());  var backup = msc.backupDB(BACKUP_FILE_NAME, parentDir);  do_check_eq(BACKUP_FILE_NAME, backup.leafName);  do_check_true(parentDir.equals(backup.parent));  parentDir.remove(true);}
meta: 10520	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/10520/85908807dace55f0d4fb729d6d3f67a3619d6f43/test_storage_connection.js/buggy/storage/test/unit/test_storage_connection.js