Simple Quck Sort example with python

quicksort.py

#!/usr/bin/env 
# -*- coding: utf-8 -*-

import unittest


""" Quicksort implementation """
def quicksort(arr):
    """ Quicksort a list

    :type arr: list
    :param arr: List to sort
    :returns: list -- Sorted list
    """
    if not arr:
        return []

    pivots = [x for x in arr if x == arr[0]]
    lesser = quicksort([x for x in arr if x < arr[0]])
    greater = quicksort([x for x in arr if x > arr[0]])

    return lesser + pivots + greater



class TestQuickSort(unittest.TestCase):

    
    def setUp(self):
        pass

    def test_emptylist(self):

        self.assertEqual(quicksort([]), [])

    def test_onesizelist(self):

        self.assertEqual(quicksort([1]), [1])

    def test_sortedlist(self):

        self.assertEqual(quicksort([1, 2, 3]), [1, 2, 3])


    def test_unsortedlist(self):

        self.assertEqual(quicksort([1, 3, 2]), [1, 2, 3])

    def test_equallist(self):

        self.assertEqual(quicksort([3, 3, 3, 3, 3]), [3, 3, 3, 3, 3])


    def test_chars(self):

        self.assertEqual(quicksort(list('street')), ['e', 'e', 'r', 's', 't', 't'])



if __name__ == '__main__':

    unittest.main()