How to test sign_in method?

user_spec.rb

require 'spec_helper'

describe 'Users' do
  describe 'Login' do
    it 'should login the user and show logout link' do
      user = FactoryGirl.create(:user)
      visit new_user_session_path
      fill_in 'Email', with: user.email
      fill_in 'Password', with: user.password
      click_button 'Sign in'
      page.should have_content('Logout')
    end
  end
end

valid_user_request_helper_spec.rb

module ValidUserRequestHelper
  def sign_in_as_a_valid_user(role = nil)
    role = 'user' if role.nil?
    @user ||= FactoryGirl.create(:user, role: role)
    visit new_user_session_path
    fill_in 'Email', with: @user.email
    fill_in 'Password', with: @user.password
    click_button 'Sign in'
  end
end