Capybara with RSpec with a Rails Engine

auth.gemspec

# auth.gemspec
require 'auth/version'

Gem::Specification.new do |s|
  ...
  
  s.add_dependency 'rails', '~> 4.0.4'
  s.add_dependency 'devise', '~> 3.2.4'
  
  s.add_development_dependency 'sqlite3'
  s.add_development_dependency 'rspec-rails', '~> 3.0.0.beta'
  s.add_development_dependency 'factory_girl_rails', '~> 4.4.1'
  s.add_development_dependency 'database_cleaner', '~> 1.2.0'
  s.add_development_dependency 'capybara', '~> 2.2.1'
end

capybara.rb

# spec/support/capybara.rb
require 'capybara/rspec'
require 'capybara/rails'

Capybara.app = Auth::Engine

RSpec.configure do |config|
  config.include RecruiticsAuth::Engine.routes.url_helpers
end

sign_in_spec.rb

# spec/features/sign_in_spec.rb
require 'spec_helper'

describe 'Sign in flow' do
  let(:user) { FactoryGirl.create :user }
  
  context 'with valid credentials' do
    it 'logs a user in' do
      visit '/auth/users/sign_in'
      within '#new_user' do
        fill_in 'Email', with: user.email
        fill_in 'Password', with: user.password
      end
      click_link 'Sign in'
      expect(page).to have_content 'Success'
    end
  end
end

spec_helper.rb

# spec/spec_helper.rb
ENV['RAILS_ENV'] = 'test'

require File.join File.dirname(__FILE__), 'dummy', 'config', 'environment.rb'

Dir[File.join File.dirname(__FILE__), 'support', '**', '*.rb'].each { |f| require f }

RSpec.configure do |config|

end