Q:

Rails Undefined Method include when including a module in `lib` dir

I cannot load my PactHelper module from my lib dir. 
# lib/pact_helper.rb

module PactHelper
    def so_something

    end
end

and
# app/controllers/registrations_controller.rb

class RegistrationsController < ApplicationController

    include PactHelper

    def new
        ...
    end
end

returns undefined method 'include' for #<RegistrationsController:0x5287cf8>
Could someone explain to me why my module is not being included? 

A:

Try:
require 'pact_helper.rb'

Above:
class RegistrationsController < ApplicationController

In:
registrations_controller.rb

