fibonacci.rb

require "test/unit"

class TestFibonachi < Test::Unit::TestCase

  def test_fibonachi_numbers
    numbers = [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765]
    numbers.each_with_index { |number, index|
      assert_equal number, Fibonachi.number(index)
    }
  end

end

class Fibonachi
  def self.number(n)
    n < 2 ? n : Fibonachi.number(n-2) + Fibonachi.number(n-1)
  end
end