diff -r 000000000000 -r 6474c204b198 services/sync/tests/unit/test_service_migratePrefs.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/services/sync/tests/unit/test_service_migratePrefs.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,70 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+Cu.import("resource://gre/modules/Preferences.jsm");
+Cu.import("resource://services-sync/util.js");
+
+function test_migrate_logging() {
+  _("Testing log pref migration.");
+  Svc.Prefs.set("log.appender.debugLog", "Warn");
+  Svc.Prefs.set("log.appender.debugLog.enabled", true);
+  do_check_true(Svc.Prefs.get("log.appender.debugLog.enabled"));
+  do_check_eq(Svc.Prefs.get("log.appender.file.level"), "Trace");
+  do_check_eq(Svc.Prefs.get("log.appender.file.logOnSuccess"), false);
+
+  Service._migratePrefs();
+
+  do_check_eq("Warn", Svc.Prefs.get("log.appender.file.level"));
+  do_check_true(Svc.Prefs.get("log.appender.file.logOnSuccess"));
+  do_check_eq(Svc.Prefs.get("log.appender.debugLog"), undefined);
+  do_check_eq(Svc.Prefs.get("log.appender.debugLog.enabled"), undefined);
+};
+
+function run_test() {
+  _("Set some prefs on the old branch");
+  let globalPref = new Preferences("");
+  globalPref.set("extensions.weave.hello", "world");
+  globalPref.set("extensions.weave.number", 42);
+  globalPref.set("extensions.weave.yes", true);
+  globalPref.set("extensions.weave.no", false);
+
+  _("Make sure the old prefs are there");
+  do_check_eq(globalPref.get("extensions.weave.hello"), "world");
+  do_check_eq(globalPref.get("extensions.weave.number"), 42);
+  do_check_eq(globalPref.get("extensions.weave.yes"), true);
+  do_check_eq(globalPref.get("extensions.weave.no"), false);
+
+  _("New prefs shouldn't exist yet");
+  do_check_eq(globalPref.get("services.sync.hello"), null);
+  do_check_eq(globalPref.get("services.sync.number"), null);
+  do_check_eq(globalPref.get("services.sync.yes"), null);
+  do_check_eq(globalPref.get("services.sync.no"), null);
+
+  _("Loading service should migrate");
+  Cu.import("resource://services-sync/service.js");
+  do_check_eq(globalPref.get("services.sync.hello"), "world");
+  do_check_eq(globalPref.get("services.sync.number"), 42);
+  do_check_eq(globalPref.get("services.sync.yes"), true);
+  do_check_eq(globalPref.get("services.sync.no"), false);
+  do_check_eq(globalPref.get("extensions.weave.hello"), null);
+  do_check_eq(globalPref.get("extensions.weave.number"), null);
+  do_check_eq(globalPref.get("extensions.weave.yes"), null);
+  do_check_eq(globalPref.get("extensions.weave.no"), null);
+
+  _("Migrating should set a pref to make sure to not re-migrate");
+  do_check_true(globalPref.get("services.sync.migrated"));
+
+  _("Make sure re-migrate doesn't happen");
+  globalPref.set("extensions.weave.tooLate", "already migrated!");
+  do_check_eq(globalPref.get("extensions.weave.tooLate"), "already migrated!");
+  do_check_eq(globalPref.get("services.sync.tooLate"), null);
+  Service._migratePrefs();
+  do_check_eq(globalPref.get("extensions.weave.tooLate"), "already migrated!");
+  do_check_eq(globalPref.get("services.sync.tooLate"), null);
+
+  _("Clearing out pref changes for other tests");
+  globalPref.resetBranch("extensions.weave.");
+  globalPref.resetBranch("services.sync.");
+
+  test_migrate_logging();
+}