The Tor Browser / file revision

 /* Any copyright is dedicated to the Public Domain.

    http://creativecommons.org/publicdomain/zero/1.0/ */

 let toplevel = this;

 Cu.import("resource://gre/modules/osfile.jsm");

 function run_test() {

   let profd = do_get_profile();

   Cu.import("resource:///modules/sessionstore/SessionFile.jsm", toplevel);

   decoder = new TextDecoder();

   pathStore = OS.Path.join(OS.Constants.Path.profileDir, "sessionstore.js");

   pathBackup = OS.Path.join(OS.Constants.Path.profileDir, "sessionstore.bak");

   let source = do_get_file("data/sessionstore_valid.js");

   source.copyTo(profd, "sessionstore.js");

   run_next_test();

 }

 let pathStore;

 let pathBackup;

 let decoder;

 // Write to the store, and check that a backup is created first

 add_task(function test_first_write_backup() {

   let content = "test_1";

   let initial_content = decoder.decode(yield OS.File.read(pathStore));

   do_check_true(!(yield OS.File.exists(pathBackup)));

   yield SessionFile.write(content);

   do_check_true(yield OS.File.exists(pathBackup));

   let backup_content = decoder.decode(yield OS.File.read(pathBackup));

   do_check_eq(initial_content, backup_content);

 });

 // Write to the store again, and check that the backup is not updated

 add_task(function test_second_write_no_backup() {

   let content = "test_2";

   let initial_content = decoder.decode(yield OS.File.read(pathStore));

   let initial_backup_content = decoder.decode(yield OS.File.read(pathBackup));

   yield SessionFile.write(content);

   let written_content = decoder.decode(yield OS.File.read(pathStore));

   do_check_eq(content, written_content);

   let backup_content = decoder.decode(yield OS.File.read(pathBackup));

   do_check_eq(initial_backup_content, backup_content);

 });