Design testing

some-model-testing.rb

class Subscription
  include Mongoid::Document
  include Mongoid::Timestamps

  belongs_to :user

  before :set_calculated_day_to_notify_on

  FREQUENCY_UNITS = [ "daily", "weekly", "monthly", "yearly" ]

  field :service,         :type => String
  field :amount,          :type => Float
  field :currency,        :type => String,  :default => "usd"
  field :started,         :type => Date

  field :frequency,                                :type => String,  :default => "monthly"
  field :day_of_frequency,                         :type => Integer
  field :number_of_days_to_notify_before_due_date, :type => Integer, :default => 2
  field :calculated_day_to_notify_on,              :type => Integer

  attr_protected :calculated_day_to_notify_on

  def self.send_monthly_email
    where(:frequency => "monthly",
          :calculated_day_to_notify_on => Date.today.day_of_month).each do |subscription|
      puts subscription.service + ', ' + subscription.user.email
    end
  end

  private
  def set_calculated_day_to_notify_on
    calculated_day = day_of_frequency - number_of_days_to_notify_before_due_date

    #make sure we're not in last month
    calculated_day = 31 - calculated_day if calculated_day < 1
    #so we can handle end of month
    calculated_day = 28 - calculated_day if calculated_day > 28

    self.calculated_day_to_notify_on = calculated_day
  end
end

class User
  include Mongoid::Document
  include Mongoid::Timestamps

  field :username
  field :password
  field :email

  has_many :subscriptions

  attr_protected :password

  def to_param
    "#{username.parameterize}"
  end
end