You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: activity_page_navigation_spec.rb
    path of file: ./repos/openproject/spec/features/activities
    
    the code of the file until where you have to start completion: #-- copyright
# OpenProject is an open source project management software.
# Copyright (C) 2012-2024 the OpenProject GmbH
#
# 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 
    
      def assert_navigating_to_diff_page_and_back_comes_back_to_the_same_page(activity_page)
        visit(activity_page)
        activity_page_url = page.current_url

        expect(page).to have_link(text: 'Details')
        expect(page.text).to include("Description changed (Details)")
        click_link('Details')

        # on diff page, click the back button
        expect(page).to have_link(text: 'Back')
        click_link('Back')

        expect(page.current_url).to eq(activity_page_url)
      end