MD Bookmarks: Prevent navigating to invalid folders

chrome/test/data/webui/md_bookmarks/actions_test.js

 // Copyright 2017 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 Test suite for action creators that depend on the page state
  * and/or have non-trivial logic.
  */
 
 suite('selectItem', function() {
@@ skipping 56 matching lines @@
     assertDeepEquals(['4'], action.items);
 
     // Anchor set to an item which doesn't exist.
     store.data.selection.anchor = '42';
 
     action = bookmarks.actions.selectItem('8', true, true, store.data);
     assertEquals('8', action.anchor);
     assertDeepEquals(['8'], action.items);
   });
 });
+
+test('selectFolder prevents selecting invalid nodes', function() {
+  var nodes = testTree(createFolder('1', [
+    createItem('2'),
+  ]));
+
+  var action = bookmarks.actions.selectFolder(ROOT_NODE_ID, nodes);
+  assertEquals(null, action);
+
+  action = bookmarks.actions.selectFolder('2', nodes);
+  assertEquals(null, action);
+
+  action = bookmarks.actions.selectFolder('42', nodes);
+  assertEquals(null, action);
+
+  action = bookmarks.actions.selectFolder('1', nodes);
+  assertEquals('select-folder', action.name);
+  assertEquals('1', action.id);
+});