Quicksort in Ruby

quicksort.rb

def qsort(list)
  return list if list.empty?

  x, *xs = list
  smaller, larger = xs.partition { |n| n < x }

  qsort(smaller) + [x] + qsort(larger)
end

describe 'qsort' do
  it 'sorts a list of numbers' do
    list = [4,8,3,2,6,2,1]
    sorted_list = qsort(list)

    expect(sorted_list).to eq([1,2,2,3,4,6,8])
  end
end