collatz_2.rb

class Collatz
  def init(i)
    buf = [i]
    while i != 1
      if (i % 2) == 0
        i = i / 2
      else
        i = i * 3 + 1
      end
      buf << i
    end
    buf = [buf.size - 1, "[#{buf.join(', ')}]"]
  end
end

require 'test/unit'

class TC_Collatz < Test::Unit::TestCase

  def setup
    @obj = Collatz.new
  end

  def test_init
    assert_equal([6, "[10, 5, 16, 8, 4, 2, 1]"], @obj.init(10))
    assert_equal([12, "[17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1]"], @obj.init(17))
    assert_equal([15, "[22, 11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1]"], @obj.init(22))
  end

end