How do I simulate a login with RSpec?

As I couldn't make @Brandan's answer work, but based on it and on this post, I've came to this solution:

# spec/support/rails_helper.rb
Dir[Rails.root.join("spec/support/**/*.rb")].each { |f| require f } # Add this at top of file

...

include ControllerMacros # Add at bottom of file

And

# spec/support/controller_macros.rb
module ControllerMacros

  def login_as_admin
    admin = FactoryGirl.create(:user_admin)
    login_as(admin)
  end

  def login_as(user)
    request.session[:user_id] = user.id
  end

end

Then on your tests you can use:

it "works" do
  login_as(FactoryGirl.create(:user))
  expect(request.session[:user_id]).not_to be_nil
end

Add helper file in spec/support/controller_helpers.rb and copy content below

module ControllerHelpers
    def sign_in(user)
      if user.nil?
        allow(request.env['warden']).to receive(:authenticate!).and_throw(:warden, {:scope => :user})
        allow(controller).to receive(:current_user).and_return(nil)
      else
        allow(request.env['warden']).to receive(:authenticate!).and_return(user)
        allow(controller).to receive(:current_user).and_return(user)
      end
    end
  end

Now add following lines in spec/rails_helper.rb or spec/spec_helper.rb file

require 'support/controller_helpers'

RSpec.configure do |config|

    config.include Devise::TestHelpers, :type => :controller
    config.include ControllerHelpers, :type => :controller

  end

Now in your controller spec file.

describe  "GET #index" do

    before :each do        
        @user=create(:user)
        sign_in @user
    end
      ...
end

Devise Official Link

The easiest way to login with a user on feature tests is to use the Warden's helper #login_as

login_as some_user

The answer depends on your authentication implementation. Normally, when a user logs in, you'll set a session variable to remember that user, something like session[:user_id]. Your controllers will check for a login in a before_filter and redirect if no such session variable exists. I assume you're already doing something like this.

To get this working in your tests, you have to manually insert the user information into the session. Here's part of what we use at work:

# spec/support/spec_test_helper.rb
module SpecTestHelper   
  def login_admin
    login(:admin)
  end

  def login(user)
    user = User.where(:login => user.to_s).first if user.is_a?(Symbol)
    request.session[:user] = user.id
  end

  def current_user
    User.find(request.session[:user])
  end
end

# spec/spec_helper.rb
RSpec.configure do |config|
  config.include SpecTestHelper, :type => :controller
end

Now in any of our controller examples, we can call login(some_user) to simulate logging in as that user.

---

I should also mention that it looks like you're doing integration testing in this controller test. As a rule, your controller tests should only be simulating requests to individual controller actions, like:

it 'should be successful' do
  get :index
  response.should be_success
end

This specifically tests a single controller action, which is what you want in a set of controller tests. Then you can use Capybara/Cucumber for end-to-end integration testing of forms, views, and controllers.