let in rspec is one of my favorite features. The decent_exposure is similar to let, but it ends up doing way more for you than I want it to. I have been doing mostly API work in Rails recently so it doesn’t fit.

To fix this I ended up writing my own simple version of let to use in my controllers.

lib/let.rb

def self.let(method, &block)
  define_method(method) do
    @lets ||= {}
    @lets[method] ||= instance_eval(&block)
  end
end

Since I ended up pasting this code in most of the projects I’m in, I ended up writing a gem letter. It’s simple to use.

app/controllers/application_controller.rb

class ApplicationController
  extend Letter

  let(:current_user) { User.find(session[:user_id]) }
end

Currently this gem doesn’t work if you have views. So a simple addition to make it work with views would be:

app/controllers/application_controller.rb

class ApplicationController
  extend Letter

  def self.let(method, *args)
    super
    helper_method(method)
  end

  let(:current_user) { User.find(session[:user_id]) }
end