Add unit tests.

iron-menu-behavior.html

@@ -98,8 +98,9 @@
      * other items.
      *
      * Reset the aria-selected attribute based on the current selection state.
-     * As _applySelection notes, we need to set aria-selected to false to items,
-     * even in their initial state, not just when they become deselected.
+     * As _applySelection notes, we need to set aria-selected to false for
+     * unselected items, even in their initial state, not just when they become
+     * deselected.
      */
     _resetItemAttributes: function() {
       var selectedItem = this.multi ? (this.selectedItems && this.selectedItems[0]) : this.selectedItem;

test/iron-menu-behavior.html

@@ -497,6 +497,29 @@
             done();
           });
         });
+
+        test('aria-selected attribute for items defaults to false', function() {
+          var menu = fixture('basic');
+          var selectedValues = menu.items.map(function(item) {
+            return item.getAttribute('aria-selected');
+          });
+          assert.deepEqual(selectedValues, ['false', 'false', 'false']);
+        });
+
+        test('aria-selected attribute reflects item selection state', function() {
+          var menu = fixture('basic');
+          var item0 = menu.items[0];
+          var item1 = menu.items[1];
+          assert.equal(item0.getAttribute('aria-selected'), 'false');
+          assert.equal(item1.getAttribute('aria-selected'), 'false');
+          menu.selected = 0;
+          assert.equal(item0.getAttribute('aria-selected'), 'true');
+          assert.equal(item1.getAttribute('aria-selected'), 'false');
+          menu.selected = 1;
+          assert.equal(item0.getAttribute('aria-selected'), 'false');
+          assert.equal(item1.getAttribute('aria-selected'), 'true');
+        });
+
       });
     </script>
   </body>