diff -r 000000000000 -r 6474c204b198 services/sync/tests/unit/test_prefs_store.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/services/sync/tests/unit/test_prefs_store.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,133 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+Cu.import("resource://gre/modules/LightweightThemeManager.jsm");
+Cu.import("resource://gre/modules/Preferences.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://services-common/utils.js");
+Cu.import("resource://services-sync/engines/prefs.js");
+Cu.import("resource://services-sync/service.js");
+Cu.import("resource://services-sync/util.js");
+
+const PREFS_GUID = CommonUtils.encodeBase64URL(Services.appinfo.ID);
+
+loadAddonTestFunctions();
+startupManager();
+
+function makePersona(id) {
+  return {
+    id: id || Math.random().toString(),
+    name: Math.random().toString(),
+    headerURL: "http://localhost:1234/a"
+  };
+}
+
+function run_test() {
+  let store = Service.engineManager.get("prefs")._store;
+  let prefs = new Preferences();
+  try {
+
+    _("Test fixtures.");
+    Svc.Prefs.set("prefs.sync.testing.int", true);
+    Svc.Prefs.set("prefs.sync.testing.string", true);
+    Svc.Prefs.set("prefs.sync.testing.bool", true);
+    Svc.Prefs.set("prefs.sync.testing.dont.change", true);
+    Svc.Prefs.set("prefs.sync.testing.turned.off", false);
+    Svc.Prefs.set("prefs.sync.testing.nonexistent", true);
+
+    prefs.set("testing.int", 123);
+    prefs.set("testing.string", "ohai");
+    prefs.set("testing.bool", true);
+    prefs.set("testing.dont.change", "Please don't change me.");
+    prefs.set("testing.turned.off", "I won't get synced.");
+    prefs.set("testing.not.turned.on", "I won't get synced either!");
+
+    _("The GUID corresponds to XUL App ID.");
+    let allIDs = store.getAllIDs();
+    let ids = Object.keys(allIDs);
+    do_check_eq(ids.length, 1);
+    do_check_eq(ids[0], PREFS_GUID);
+    do_check_true(allIDs[PREFS_GUID], true);
+
+    do_check_true(store.itemExists(PREFS_GUID));
+    do_check_false(store.itemExists("random-gibberish"));
+
+    _("Unknown prefs record is created as deleted.");
+    let record = store.createRecord("random-gibberish", "prefs");
+    do_check_true(record.deleted);
+
+    _("Prefs record contains only prefs that should be synced.");
+    record = store.createRecord(PREFS_GUID, "prefs");
+    do_check_eq(record.value["testing.int"], 123);
+    do_check_eq(record.value["testing.string"], "ohai");
+    do_check_eq(record.value["testing.bool"], true);
+    do_check_eq(record.value["testing.nonexistent"], null);
+    do_check_false("testing.turned.off" in record.value);
+    do_check_false("testing.not.turned.on" in record.value);
+
+    _("Prefs record contains pref sync prefs too.");
+    do_check_eq(record.value["services.sync.prefs.sync.testing.int"], true);
+    do_check_eq(record.value["services.sync.prefs.sync.testing.string"], true);
+    do_check_eq(record.value["services.sync.prefs.sync.testing.bool"], true);
+    do_check_eq(record.value["services.sync.prefs.sync.testing.dont.change"], true);
+    do_check_eq(record.value["services.sync.prefs.sync.testing.turned.off"], false);
+    do_check_eq(record.value["services.sync.prefs.sync.testing.nonexistent"], true);
+
+    _("Update some prefs, including one that's to be reset/deleted.");
+    Svc.Prefs.set("testing.deleteme", "I'm going to be deleted!");
+    record = new PrefRec("prefs", PREFS_GUID);
+    record.value = {
+      "testing.int": 42,
+      "testing.string": "im in ur prefs",
+      "testing.bool": false,
+      "testing.deleteme": null,
+      "services.sync.prefs.sync.testing.somepref": true
+    };
+    store.update(record);
+    do_check_eq(prefs.get("testing.int"), 42);
+    do_check_eq(prefs.get("testing.string"), "im in ur prefs");
+    do_check_eq(prefs.get("testing.bool"), false);
+    do_check_eq(prefs.get("testing.deleteme"), undefined);
+    do_check_eq(prefs.get("testing.dont.change"), "Please don't change me.");
+    do_check_eq(Svc.Prefs.get("prefs.sync.testing.somepref"), true);
+
+    _("Enable persona");
+    // Ensure we don't go to the network to fetch personas and end up leaking
+    // stuff.
+    Services.io.offline = true;
+    do_check_false(!!prefs.get("lightweightThemes.isThemeSelected"));
+    do_check_eq(LightweightThemeManager.currentTheme, null);
+
+    let persona1 = makePersona();
+    let persona2 = makePersona();
+    let usedThemes = JSON.stringify([persona1, persona2]);
+    record.value = {
+      "lightweightThemes.isThemeSelected": true,
+      "lightweightThemes.usedThemes": usedThemes
+    };
+    store.update(record);
+    do_check_true(prefs.get("lightweightThemes.isThemeSelected"));
+    do_check_true(Utils.deepEquals(LightweightThemeManager.currentTheme,
+                  persona1));
+
+    _("Disable persona");
+    record.value = {
+      "lightweightThemes.isThemeSelected": false,
+      "lightweightThemes.usedThemes": usedThemes
+    };
+    store.update(record);
+    do_check_false(prefs.get("lightweightThemes.isThemeSelected"));
+    do_check_eq(LightweightThemeManager.currentTheme, null);
+
+    _("Only the current app's preferences are applied.");
+    record = new PrefRec("prefs", "some-fake-app");
+    record.value = {
+      "testing.int": 98
+    };
+    store.update(record);
+    do_check_eq(prefs.get("testing.int"), 42);
+
+  } finally {
+    prefs.resetBranch("");
+  }
+}