Swap and correct WikiMenuItems titles and names

Previously, the `title` attribute of a WikiMenuItem was used to identify
a page that was linked to.

With slugs, that makes no sense. We swap the name and title usage so
that:

1. Name is used for the wiki_page slug that is being linked to
2. Title is used for the displayed name

db/migrate/20160803094931_wiki_menu_titles_to_slug.rb

@@ -0,0 +1,57 @@
+class WikiMenuTitlesToSlug < ActiveRecord::Migration
+  def up
+    migrate_menu_items
+  end
+
+  def down
+    rollback_menu_items
+  end
+
+  ##
+  # Fix lookup of wiki pages in menu items by referencing the actual slug in the title attribute.
+  # As the title attribute is fixed from MenuItem, and the name was used, swap the two around
+  # to avoid confusing the actual title of the menu item (previously == name).
+  def migrate_menu_items
+    ActiveRecord::Base.transaction do
+      ::MenuItems::WikiMenuItem.includes(:wiki).find_each do |item|
+        # Find the page
+        wiki_page = item.wiki.find_page(item.title)
+
+        # Set the title to the actual slug
+        # If the page could not be found, migrate the title to form a slug
+        slug = wiki_page.nil? ? item.title.to_url : wiki_page.slug
+
+        # Use the name to set the title.
+        # This clears up the previously irritating mixup of the two.
+        menu_item_title = item.name
+
+        item.update_columns(title: menu_item_title, name: slug)
+      end
+    end
+  end
+
+  ##
+  #
+  # Restore the old title wherever possible
+  # This tries to remove the slug usages without guaranteeing that links
+  # will be valid afterwards.
+  def rollback_menu_items
+    ActiveRecord::Base.transaction do
+      ::MenuItems::WikiMenuItem.includes(:wiki).find_each do |item|
+        # Find the page
+        wiki_page = item.wiki.find_page(item.title)
+
+        # Restore the switch of title and name
+        old_name = item.title
+        old_title =
+          if wiki_page.present?
+            wiki_page.title
+          else
+            item.name
+          end
+
+        item.update_columns(title: old_title, name: old_name)
+      end
+    end
+  end
+end

spec/features/wiki/wiki_menu_item_migration_spec.rb

@@ -0,0 +1,78 @@
+#-- copyright
+# OpenProject is a project management system.
+# Copyright (C) 2012-2015 the OpenProject Foundation (OPF)
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See doc/COPYRIGHT.rdoc for more details.
+#++
+
+require 'spec_helper'
+require Rails.root.join('db/migrate/20160803094931_wiki_menu_titles_to_slug.rb')
+
+describe 'Wiki menu_items migration', type: :feature do
+  let(:project) { FactoryGirl.create :project }
+  let(:wiki_page) {
+    FactoryGirl.create :wiki_page_with_content,
+                       wiki: project.wiki,
+                       title: 'Base de donées'
+  }
+  let!(:menu_item) {
+    FactoryGirl.create(:wiki_menu_item,
+                       :with_menu_item_options,
+                       wiki: project.wiki,
+                       name: 'My linked page',
+                       title: wiki_page.title)
+  }
+
+  before do
+    project.wiki.pages << wiki_page
+
+    # Run the title replacement of the migration
+    ::WikiMenuTitlesToSlug.new.migrate_menu_items
+
+    menu_item.reload
+  end
+
+  it 'updates the menu item' do
+    expect(menu_item.name).to eq(wiki_page.slug)
+    expect(menu_item.title).to eq('My linked page')
+  end
+
+
+  describe 'visiting the wiki' do
+    let(:user) { FactoryGirl.create :admin }
+
+    before do
+      login_as(user)
+    end
+
+    it 'shows the menu item' do
+      visit project_wiki_path(project, project.wiki)
+      link = page.find('#menu-sidebar a.icon-wiki', text: menu_item.name)
+      link.click
+
+      expect(page).to have_selector('.wiki-title', text: wiki_page.title)
+      expect(current_path).to eq(project_wiki_path(project, wiki_page.slug))
+    end
+  end
+end