Mergesort implementation

README.md

saw a project of a friend of mine ( http://hugopeixoto.net/mergesort.xhtml ) and tried to spice up the ruby implementation

mergesort.rb

def merge(a,b)
  r = []
  r << (a.first < b.first ? a : b).shift until a.empty? or b.empty?

  r+a+b
end

def mergesort(list)
  return list if list.size <= 1

  m = list.size / 2
  merge( mergesort(list[0...m]), mergesort(list[m..-1]) )
end

puts mergesort( [10, 9, 8, 5, 6, 7, 4, 3, 2, 1] )

mergesort_test.rb

require 'test/unit'
require 'mergesort'

ARRAY_UNSORTED = [10, 9, 8, 4, 5, 6, 7, 3, 2, 1]
ARRAY_SORTED   = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

class MergeSortTest < Test::Unit::TestCase
  def test_mergesort_implementation
    assert_equal ARRAY_SORTED, mergesort(ARRAY_UNSORTED)
  end
end