Post_102.3.rb

#All our fields require presence, so we create a base class

  class BaseValidation

    def absent?(value)
      value.nil? || value.empty?
    end
  end  
  
  class DateValidation < BaseValidation

    def check_for_errors(value)
      if absent?(value) || invalid_format?(value) || invalid_date?(value)
        'Invalid Date: Be sure to use mm/dd/yyyy format.'
      end
    end

    def invalid_format?(value)
      !/\d\d\/\d\d\/\d\d\d\d/.match(value)
    end

    def invalid_date?(value)
      Date.today <=  Date.strptime(value, '%m/%d/%Y')
    end
  end
  
  class IncludedValidation < BaseValidation
    attr_reader :valid_values

    def initialize(valid_values)
      @valid_values = valid_values
    end

    def check_for_errors(value)
      if absent?(value) || !valid_values.include?(value)
        'That is not a valid choice'
      end
    end
  end