AppListModel / AppsGridView: Better error handling for corner cases.

ui/app_list/app_list_model_unittest.cc

 // Copyright 2013 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.
 
 #include "ui/app_list/app_list_model.h"
 
 #include <map>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 274 matching lines @@
       folder, folder->item_list()->item_at(num_observed_apps)));
 }
 
 TEST_F(AppListModelFolderTest, MergeItems) {
   model_.PopulateApps(3);
   ASSERT_EQ(3u, model_.top_level_item_list()->item_count());
   AppListItem* item0 = model_.top_level_item_list()->item_at(0);
   AppListItem* item1 = model_.top_level_item_list()->item_at(1);
   AppListItem* item2 = model_.top_level_item_list()->item_at(2);
 
+  // Merge an item onto a non-existent target.
+  EXPECT_EQ(std::string(), model_.MergeItems("nonexistent", item0->id()));
+  ASSERT_EQ(3u, model_.top_level_item_list()->item_count());
+
+  // Merge a non-existent item onto a target.
+  EXPECT_EQ(std::string(), model_.MergeItems(item0->id(), "nonexistent"));
+  ASSERT_EQ(3u, model_.top_level_item_list()->item_count());
+
+  // Merge an item onto itself (should have no effect). This should not be
+  // possible, but there have been bugs in the past that made it possible (see
+  // http://crbug.com/415530), so it should be handled correctly.
+  EXPECT_EQ(std::string(), model_.MergeItems(item0->id(), item0->id()));
+  ASSERT_EQ(3u, model_.top_level_item_list()->item_count());
+
   // Merge two items.
   std::string folder1_id = model_.MergeItems(item0->id(), item1->id());
   ASSERT_EQ(2u, model_.top_level_item_list()->item_count());  // Folder + 1 item
   AppListFolderItem* folder1_item = model_.FindFolderItem(folder1_id);
   ASSERT_TRUE(folder1_item);
   EXPECT_EQ("Item 0,Item 1", GetItemListContents(folder1_item->item_list()));
 
+  // Merge an item onto an item that is already in a folder (should have no
+  // effect). This should not be possible, but it should be handled correctly
+  // if it does happen.
+  EXPECT_EQ(std::string(), model_.MergeItems(item1->id(), item2->id()));
+  ASSERT_EQ(2u, model_.top_level_item_list()->item_count());  // Folder + 1 item
+  EXPECT_EQ("Item 0,Item 1", GetItemListContents(folder1_item->item_list()));
+
   // Merge an item from the new folder into the third item.
   std::string folder2_id = model_.MergeItems(item2->id(), item1->id());
   ASSERT_EQ(2u, model_.top_level_item_list()->item_count());  // 2 folders
   AppListFolderItem* folder2_item = model_.FindFolderItem(folder2_id);
   EXPECT_EQ("Item 0", GetItemListContents(folder1_item->item_list()));
   EXPECT_EQ("Item 2,Item 1", GetItemListContents(folder2_item->item_list()));
 
   // Merge the remaining item to the new folder, ensure it is added to the end.
   std::string folder_id = model_.MergeItems(folder2_id, item0->id());
   EXPECT_EQ(folder2_id, folder_id);
   EXPECT_EQ("Item 2,Item 1,Item 0",
             GetItemListContents(folder2_item->item_list()));
 
   // The empty folder should be deleted.
   folder1_item = model_.FindFolderItem(folder1_id);
   EXPECT_FALSE(folder1_item);
+  EXPECT_EQ(1u, model_.top_level_item_list()->item_count());  // 1 folder
 }
 
 TEST_F(AppListModelFolderTest, AddItemToFolder) {
   AppListFolderItem* folder =
       new AppListFolderItem("folder1", AppListFolderItem::FOLDER_TYPE_NORMAL);
   model_.AddItem(folder);
   AppListItem* item0 = new AppListItem("Item 0");
   model_.AddItemToFolder(item0, folder->id());
   ASSERT_EQ(1u, model_.top_level_item_list()->item_count());
   AppListFolderItem* folder_item = model_.FindFolderItem(folder->id());
@@ skipping 165 matching lines @@
   model_.SetFoldersEnabled(false);
   ASSERT_FALSE(model_.FindFolderItem(folder_id));
   ASSERT_TRUE(model_.FindFolderItem(oem_folder_id));
   EXPECT_EQ("Item 0,Item 1,oem_folder", GetModelContents());
 
   // Ensure folder creation fails.
   EXPECT_EQ(std::string(), model_.MergeItems(item0->id(), item1->id()));
 }
 
 }  // namespace app_list