random_testing.rb

require 'securerandom'

def secure_random_test(max = 1_000_000)
  ratio = (0...max).map do
    SecureRandom.random_number(max)
  end.uniq.count.to_f/max.to_f

  (ratio - (1 - 1/Math::E)).abs
end

puts "SecureRandom: #{secure_random_test}"

def rand_test(max = 1_000_000)
  ratio = (0...max).map do
    rand(max)
  end.uniq.count.to_f/max.to_f

  (ratio - (1 - 1/Math::E)).abs
end

puts "rand: #{rand_test}"