Ruby implementation of Secret Santa -

the problem stated follows: there list of persons, each having first name , last name. people having same last name belong same family. aim chose secret santa each person such secret santa ofcourse not same person, nor belong same family. i've taken liberty of assigning santa same family if there no other choice.

i have following code achieve , passing tests - i'm not confident if code produces correct results in cases.

in case algorithm not correct i'll appreciate if can explain why algorithm fails, review of code quite helpful.

the main method in code assign_angels, , have tried return self of methods following east oriented code

this problem taken ruby quiz: secret santa

i'm using equalizer module equality checking equalizer

require 'set' require 'equalizer'  class people    include equalizer.new(:people)    def initialize personlist = []     @people = array(personlist).to_set   end    def add person     @people.add person     self   end    def assign_angels     @people.each |person|       eligible_santas         .preferably_of_different_family(person)         .assign_angel_to_one(person)     end     self   end    def to_s      @people.map { |person| person.to_s }   end    protected    def sample     @people.to_a.sample || nilperson.new   end    def size     @people.size   end    def assign_angel_to_one person     sample.assign_angel person     self   end    def eligible_santas     people.new @people.select { |person| person.angel == nil }   end    def preferably_of_different_family person_a     different_family = people_of_different_family person_a     if different_family.size == 0       same_family = people_of_same_family person_a       if(same_family.size == 0)         return people.new nilperson.new       end       return same_family     end     return different_family   end    def people_of_different_family person_a     people.new @people.select { |person| person unless person.is_family? person_a }   end    def people_of_same_family person_a     people.new @people.select { |person| person unless person == person_a }   end    attr_reader :people end