[Common UI] Complete remaining specs

Complete remaining specs to achieve full test coverage
for common user interface bundles being transitioned
as part of WTD-574.

platform/commonUI/browse/test/windowing/FullscreenActionSpec.js

@@ -1,4 +1,4 @@
-/*global define,Promise,describe,it,expect,beforeEach,waitsFor,jasmine*/
+/*global define,Promise,describe,it,expect,beforeEach,waitsFor,jasmine,afterEach,screenfull*/
 
 /**
  * MCTRepresentationSpec. Created by vwoeltje on 11/6/14.
@@ -9,6 +9,31 @@ define(
         "use strict";
 
         describe("The fullscreen action", function () {
+            var action,
+                oldToggle;
+
+            beforeEach(function () {
+                // Screenfull is not shimmed or injected, so
+                // we need to spy on it in the global scope.
+                oldToggle = screenfull.toggle;
+
+                screenfull.toggle = jasmine.createSpy("toggle");
+
+                action = new FullscreenAction({});
+            });
+
+            afterEach(function () {
+                screenfull.toggle = oldToggle;
+            });
+
+            it("toggles fullscreen mode when performed", function () {
+                action.perform();
+                expect(screenfull.toggle).toHaveBeenCalled();
+            });
+
+            it("provides displayable metadata", function () {
+                expect(action.getMetadata().glyph).toBeDefined();
+            });
 
         });
     }