test.py

#!/usr/bin/env python3
import unittest
from harrypotterkata import get_lowest_price
  
class TestKata(unittest.TestCase):
    
    # Ref: https://codingdojo.org/kata/Potter/
    def test_basics(self):
        self.assertEqual(0, get_lowest_price([]))
        self.assertEqual(8, get_lowest_price([1]))
    
    def test_simple_discounts(self):
        self.assertEqual(8 * 2 * 0.95, get_lowest_price([0, 1]))
        self.assertEqual(8 * 3 * 0.9, get_lowest_price([0, 2, 4]))
        self.assertEqual(8 * 4 * 0.8, get_lowest_price([0, 1, 2, 4]))
        self.assertEqual(8 * 5 * 0.75, get_lowest_price([0, 1, 2, 3, 4]))

    def test_several_discounts(self):
        self.assertEqual(8 + (8 * 2 * 0.95), get_lowest_price([0, 0, 1]))
        self.assertEqual(2 * (8 * 2 * 0.95), get_lowest_price([0, 0, 1, 1]))
        self.assertEqual((8 * 4 * 0.8) + (8 * 2 * 0.95), get_lowest_price([0, 0, 1, 2, 2, 3]))
        self.assertEqual(8 + (8 * 5 * 0.75), get_lowest_price([0, 1, 1, 2, 3, 4]))

    def test_edge_cases(self):
        self.assertEqual(2 * (8 * 4 * 0.8), get_lowest_price([0, 0, 1, 1, 2, 2, 3, 4]))
        self.assertEqual(3 * (8 * 5 * 0.75) + 2 * (8 * 4 * 0.8), 
            get_lowest_price([0, 0, 0, 0, 0, 
                              1, 1, 1, 1, 1, 
                              2, 2, 2, 2, 
                              3, 3, 3, 3, 3, 
                              4, 4, 4, 4]))
  
if __name__ == '__main__':
    unittest.main()