railstutorial 5.3.4 NoMethodError: undefined method `full_title' for #<RSpec::ExampleGroups::StaticPages::HomePage:0x007fbd94a315e8>

spec_helper.rb

require "support/utilities"

RSpec.configure do |config|
  config.expect_with :rspec do |expectations|
    expectations.include_chain_clauses_in_custom_matcher_descriptions = true
  end

  config.mock_with :rspec do |mocks|
    mocks.verify_partial_doubles = true
  end

end

static_pages_spec.rb

require 'spec_helper'
require 'rails_helper'
# require 'support/utilities'

describe "Static pages" do

  subject { page }

  describe "Home page" do

    before { visit root_path }

    it { should have_content('Sample App') }
    it { should have_title(full_title('')) }
    it { should_not have_title('| Home') }

  end

  describe "Help page" do

    before { visit help_path }

    it { should have_content('Help') }
    it { should have_title(full_title('Help')) }

  end

  describe "About page" do

    before { visit about_path }

    it { should have_content('About Us') }
    it { should have_title(full_title('About Us')) }

  end

  describe "Contact page" do

    before { visit contact_path }

    it { should have_content('Contact') }
    it { should have_title(full_title('Contact')) }

  end
end

utilities.rb

def full_title(page_title)
  base_title = "Ruby on Rails Tutorial Sample App"
  if page_title.empty?
    base_title
  else
    "#{base_title} | #{page_title}"
  end
end