I was able to use Devise's `sign_in` method to log in a user in my controller specs. But now that I'm removing Devise from my application, I'm not quite sure how to get similar functionality working with just Warden on its own.

How should I go about setting up `spec/spec_helper.rb` and related `spec/support/*.rb` files to get Warden running within controller specs sufficiently?

I've tried setting up a file at `spec/support/warden.rb` with these contents:

```
RSpec.configure do |config|
  config.include Warden::Test::Helpers

  config.after do
    Warden.test_reset!
  end
end

```

Then I have `before` calls similar to this to authenticate a `user` factory:

```
before { login_as FactoryGirl.create(:user) }

```

But here is the error that I keep seeing:

```
NameError:
  undefined method `user' for nil:NilClass

```

This error traces back to my `authenticate_user!` method in the controller:

```
def authenticate_user!
  redirect_to login_path, notice: "You need to sign in or sign up before continuing." if env['warden'].user.nil?
end

```

I'd appreciate any guidance that anyone could provide.