test.rb

def fizzbuzz(n)
  if n % 3 == 0 && n % 5 == 0
    'FizzBuzz'
  elsif n % 3 == 0
    'Fizz'
  elsif n % 5 == 0
    'Buzz'
  else
    n
  end
end

(1..20).each do |n|
  puts fizzbuzz(n)
end