Paris Workshop ROT 13

rot_13.rb

class EncryptionEngine
  def self.encrypt(string)
    results = ''
    string.each_char do |l|
      results += rot(l)
    end
    results
  end

  def self.decrypt(string)
    results = ''
    string.each_char do |l|
      results += rot(l, 13)
    end
    results
  end

  def self.rot(letter, num = 13)
    case letter
    when /^([a-m]|[A-M])$/
      x = (letter.ord + num).chr
    when /^([n-z]|[N-Z])$/
      x = (letter.ord - num).chr
    else
      letter
    end
  end
end

def main
  test1
  test2
end

def test1
  text = 'HELLO friend'
  if 'URYYB sevraq' == EncryptionEngine.encrypt(text)
    puts '.'
  else
    puts 'TEST 1 failed'
    puts "actual: #{EncryptionEngine.encrypt(text)}"
  end
end

def test2
  text = 'URYYB sevraq'
  if 'HELLO friend' == EncryptionEngine.decrypt(text)
    puts '.'
  else
    puts 'TEST 2 failed'
    puts "actual: #{EncryptionEngine.decrypt(text)}"
  end
end

main