Thoughts on the birthday greeting kata

gistfile1.rb

# As seen from the example below, you could imagine a Rails application 
# "depending" on this application logic. Controllers would act as the 'main' 
# instantiating collaborators to inject into the service (aka use case).

# "Note that the collaborators of the birthdayService objects are injected in 
# it. Ideally domain code should never use the new operator. The new operator is
# called from outside the domain code, to set up an aggregate of objects that 
# collaborate together." - http://matteo.vaccari.name/blog/archives/154

class BirthdayService
  def initialize(employee_repository, email_service)
    @employee_repository, @email_service = employee_repository, email_service
  end

  def send_greeting(date)
    birthday_people(date).each do |birthday_person|
      email_service.deliver_birthday_greeting(birthday_person)
    end
  end

  private

  def birthday_people(date)
    @employee_repository.find_all_by_date_of_birth(date)
  end
end

employee_repository = EmployeeFileRepository.new # or Employee < ActiveRecord::Base
email_service = ???

birthday_service = BirthdayService.new(employee_repository, email_service)
birthday_service.send_greeting(Date.today)