Insertion sort in ruby

insertion_sort.rb

# Insertion sort (inefficient on large lists)

require 'test/unit'

def sort(a)
  n = a.size - 1
  1.upto(n) do |i|
    new_value = a[i]
    j = i
    while j > 0 && a[j - 1] > new_value do
      a[j] = a[j - 1]
      j -= 1
    end
    a[j] = new_value
  end
  a
end

class TestInsertionSort < Test::Unit::TestCase
  def test_insertion_sort
    arr = sort([6,3,5,2])
    assert_operator arr[0], :<, arr[1]
    assert_operator arr[2], :<, arr[3]
  end
end