MD Bookmarks: Prevent navigating to invalid folders

chrome/test/data/webui/md_bookmarks/router_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.
 
 suite('<bookmarks-router>', function() {
   var store;
   var router;
 
   function navigateTo(route) {
     window.history.replaceState({}, '', route);
     window.dispatchEvent(new CustomEvent('location-changed'));
   }
 
   setup(function() {
     store = new bookmarks.TestStore({
+      nodes: testTree(createFolder('1', [createFolder('2', [])])),
       selectedId: '1',
       search: {
         term: '',
       },
     });
     bookmarks.Store.instance_ = store;
 
     router = document.createElement('bookmarks-router');
     replaceBody(router);
   });
 
   test('search updates from route', function() {
     navigateTo('/?q=bleep');
     assertEquals('start-search', store.lastAction.name);
     assertEquals('bleep', store.lastAction.term);
   });
 
   test('selected folder updates from route', function() {
-    navigateTo('/?id=5');
+    navigateTo('/?id=2');
     assertEquals('select-folder', store.lastAction.name);
-    assertEquals('5', store.lastAction.id);
+    assertEquals('2', store.lastAction.id);
   });
 
   test('route updates from ID', function() {
-    store.data.selectedFolder = '6';
+    store.data.selectedFolder = '2';
     store.notifyObservers();
 
     return Promise.resolve().then(function() {
-      assertEquals('chrome://bookmarks/?id=6', window.location.href);
+      assertEquals('chrome://bookmarks/?id=2', window.location.href);
     });
   });
 
   test('route updates from search', function() {
     store.data.search = {term: 'bloop'};
     store.notifyObservers();
 
     return Promise.resolve()
         .then(function() {
           assertEquals('chrome://bookmarks/?q=bloop', window.location.href);
@@ skipping 16 matching lines @@
     }
 
     if (window.searchedQuery) {
       verifySearch(window.searchedQuery);
       return;
     }
 
     chrome.bookmarks.search = verifySearch;
   });
 });