diff -r 000000000000 -r 6474c204b198 browser/components/customizableui/test/browser_877178_unregisterArea.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/customizableui/test/browser_877178_unregisterArea.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+registerCleanupFunction(removeCustomToolbars);
+
+// Sanity checks
+add_task(function sanityChecks() {
+  SimpleTest.doesThrow(function() CustomizableUI.registerArea("@foo"),
+                       "Registering areas with an invalid ID should throw.");
+
+  SimpleTest.doesThrow(function() CustomizableUI.registerArea([]),
+                       "Registering areas with an invalid ID should throw.");
+
+  SimpleTest.doesThrow(function() CustomizableUI.unregisterArea("@foo"),
+                       "Unregistering areas with an invalid ID should throw.");
+
+  SimpleTest.doesThrow(function() CustomizableUI.unregisterArea([]),
+                       "Unregistering areas with an invalid ID should throw.");
+
+  SimpleTest.doesThrow(function() CustomizableUI.unregisterArea("unknown"),
+                       "Unregistering an area that's not registered should throw.");
+});
+
+// Check areas are loaded with their default placements.
+add_task(function checkLoadedAres() {
+  ok(CustomizableUI.inDefaultState, "Everything should be in its default state.");
+});
+
+// Check registering and unregistering a new area.
+add_task(function checkRegisteringAndUnregistering() {
+  const kToolbarId = "test-registration-toolbar";
+  const kButtonId = "test-registration-button";
+  createDummyXULButton(kButtonId);
+  createToolbarWithPlacements(kToolbarId, ["spring", kButtonId, "spring"]);
+  assertAreaPlacements(kToolbarId,
+                       [/customizableui-special-spring\d+/,
+                        kButtonId,
+                        /customizableui-special-spring\d+/]);
+  ok(!CustomizableUI.inDefaultState, "With a new toolbar it is no longer in a default state.");
+  removeCustomToolbars(); // Will call unregisterArea for us
+  ok(CustomizableUI.inDefaultState, "When the toolbar is unregistered, " +
+     "everything will return to the default state.");
+});
+
+add_task(function asyncCleanup() {
+  yield resetCustomization();
+});