Fisher-Yates Shuffle

main.py

import random


def shuffle(ary):
    old_ary = ary[:]
    a = len(ary)
    b = a - 1
    for d in range(b, 0, -1):
        e = random.randint(0, d - 1)
        ary[d], ary[e] = ary[e], ary[d]

    return ary

test.py

from main import shuffle
import unittest


class TestShuffle(unittest.TestCase):
    def test_shuffle(self):
        numbers = [a for a in range(1, 101)]
        shuffled = shuffle(numbers)
        print(shuffled)
        self.assertEqual(len(set(shuffled) & set(numbers)), len(numbers))


if __name__ == '__main__':
    unittest.main()