MD WebUI: fix action menu initial focus to be more like context menus

chrome/test/data/webui/cr_elements/cr_action_menu_test.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview Tests for cr-action-menu element. Runs as an interactive UI
  * test, since many of these tests check focus behavior.
  */
 suite('CrActionMenu', function() {
   /** @type {?CrActionMenuElement} */
@@ skipping 18 matching lines @@
     menu = document.querySelector('dialog[is=cr-action-menu]');
     items = menu.querySelectorAll('.dropdown-item');
     assertEquals(3, items.length);
   });
 
   teardown(function() {
     if (menu.open)
       menu.close();
   });
 
-  test('focus after showing', function() {
+  function down() {
+    MockInteractions.keyDownOn(menu, 'ArrowDown', [], 'ArrowDown');
+  }
+
+  test('hidden or disabled items', function() {
     menu.showAt(document.querySelector('#dots'));
+    down();
     assertEquals(menu.root.activeElement, items[0]);
 
     menu.close();
     items[0].hidden = true;
     menu.showAt(document.querySelector('#dots'));
+    down();
     assertEquals(menu.root.activeElement, items[1]);
 
     menu.close();
-    items[1].hidden = true;
+    items[1].disabled = true;
     menu.showAt(document.querySelector('#dots'));
+    down();
     assertEquals(menu.root.activeElement, items[2]);
-
-    menu.close();
-    items[2].disabled = true;
-    menu.showAt(document.querySelector('#dots'));
-    assertEquals(null, menu.root.activeElement);
   });
 
   test('focus after down/up arrow', function() {
-    function down() {
-      MockInteractions.keyDownOn(menu, 'ArrowDown', [], 'ArrowDown');
-    }
-
     function up() {
       MockInteractions.keyDownOn(menu, 'ArrowUp', [], 'ArrowUp');
     }
 
     menu.showAt(document.querySelector('#dots'));
+
+    // The menu should be focused when shown, but not on any of the items.
+    assertEquals(menu, document.activeElement);
+    assertNotEquals(items[0], menu.root.activeElement);

[dpapad, 2017/03/18 01:03:05]

Optional nit: What is the value of menu.root.activeElement at this point? Is it
null? Perhaps you can replace all 3 assertions with a single assertion.

assertEquals(null, menu.root.activeElement);

[Dan Beam, 2017/03/18 17:55:06]

it's not null, it's a wrapper in the shadow DOM and I don't think the test
should know about it (or at least it doesn't seem useful)

+    assertNotEquals(items[1], menu.root.activeElement);
+    assertNotEquals(items[2], menu.root.activeElement);
+
+    down();
     assertEquals(items[0], menu.root.activeElement);
-
     down();
     assertEquals(items[1], menu.root.activeElement);
     down();
     assertEquals(items[2], menu.root.activeElement);
     down();
     assertEquals(items[0], menu.root.activeElement);
     up();
     assertEquals(items[2], menu.root.activeElement);
     up();
     assertEquals(items[1], menu.root.activeElement);
@@ skipping 35 matching lines @@
       MockInteractions.keyDownOn(menu, key, [], key);
       assertFalse(menu.open);
     });
   }
 
   test('close on Tab', function() { return testFocusAfterClosing('Tab'); });
   test('close on Escape', function() {
     return testFocusAfterClosing('Escape');
   });
 });