quicksort_spec.rb

include Quicksort

RSpec.describe 'Quicksort' do
  describe '#partition!' do
    it 'partitions the p..r subarray around a pivot' do
      array = [9, 7, 5, 11, 12, 2, 14, 3, 10, 4, 6]
      pivot = partition!(array, 0, array.length - 1)

      expect(pivot).to eq(4)
      expect(array).to eq([5, 2, 3, 4, 6, 7, 14, 9, 10, 11, 12])
    end

    it 'handles incomplete subarrays' do
      array = [9, 7, 5, 11, 12, 2, 14, 3, 10, 4, 6]
      pivot = partition!(array, 0, 2)

      expect(pivot).to eq(0)
      expect(array).to eq([5, 7, 9, 11, 12, 2, 14, 3, 10, 4, 6])

    end

    it 'handles zeros and negatives' do
      array = [0, -1, 2, 0]
      pivot = partition!(array, 0, array.length - 1)

      expect(pivot).to eq(2)
      expect(array).to eq([0, -1, 0, 2])
    end
  end

  describe '#quicksort!' do
    it 'sorts the specified subarray' do
      array = [9, 7, 5, 11, 12, 2, 14, 3, 10, 4, 6]
      quicksort!(array, 0, array.length - 1)

      expect(array).to eq(array.sort)
    end

    it 'handles incomplete subarrays' do
      array = [9, 7, 5, 11, 12, 2, 14, 3, 10, 4, 6]
      quicksort!(array, 0, 2)

      expect(array).to eq([5, 7, 9, 11, 12, 2, 14, 3, 10, 4, 6])
    end

    it 'handles zeros and negatives' do
      array = [0, -1, 2, 0]
      quicksort!(array, 0, array.length - 1)

      expect(array).to eq([-1, 0, 0, 2])
    end
  end
end