Josephus in Ruby - tests with RSpec

Gemfile

source 'https://rubygems.org'

ruby '1.9.3'

# RSpec
gem 'rspec-rails'

main.rb

class Main
  def calculo(n, xs)
    result_final = []

    xs.each do |x|
      base_x4 = (x / 4).floor
      result_final << (x + base_x4 + (((( x + base_x4 ) / 4 ).floor ) - base_x4))
    end

    return result_final
  end

  def calculo2(n, xs)
    result_final = []

    n_resto_4 = n % 4
    ultimo = 4 - n_resto_4
    pulos = ((5 - n_resto_4)/4).floor

    xs.each do |x|
      base_x4 = (x / 4).floor
      result1 = x + base_x4 + (((( x + base_x4 ) / 4 ).floor ) - base_x4)
      #recomecar = n * ((x/4).ceil - (x/4).floor)
      result_final << (result1 + ultimo + pulos) % n
    end

    return result_final
  end
end

spec.rb

require_relative 'main'


RSpec.describe Main do
  it { expect( Main.new.calculo2(5, [1,2,3]) ).to eq( [5,1,2] ) }
  it { expect( Main.new.calculo2(6, [1,2,3]) ).to eq( [3,5,6] ) }
  it { expect( Main.new.calculo2(7, [5,1,2]) ).to eq( [7,2,3] ) }
  it { expect( Main.new.calculo(8, [3,5,6]) ).to eq( [3,6,7] ) }
  it { expect( Main.new.calculo2(9, [3,5,6]) ).to eq( [7,1,2] ) }
  it { expect( Main.new.calculo2(10, [7,2,3]) ).to eq( [1,5,6] ) }
  it { expect( Main.new.calculo2(11, [3,6,7]) ).to eq( [5,9,10] ) }
  it { expect( Main.new.calculo(12, [7,1,2]) ).to eq( [9,1,2] ) }
  it { expect( Main.new.calculo2(13, [7,1,2]) ).to eq( [13,5,6] ) }
  it { expect( Main.new.calculo2(14, [1,5,6]) ).to eq( [3,9,10] ) }
  it { expect( Main.new.calculo2(15, [5,9,10]) ).to eq( [7,13,14] ) }
  it { expect( Main.new.calculo(16, [9,1,2]) ).to eq( [11,1,2] ) }
  it { expect( Main.new.calculo2(17, [9,1,2]) ).to eq( [15,5,6] ) }
end