Python Password Validation

validate.py

#!/usr/bin/env python3
import unittest

"""Valid passwords
 - are between 8 and 20 characters long
 - contain at least one number
 - have at least one uppercase and one lowercase character
 - have a special char of !"§$%&/()=?

"""

def validate(password):
    length_ok = len(password) in range(8, 21)
    has_number = any(c.isdigit() for c in password)
    has_lower = bool(set(password) & set(password.lower()))
    has_upper = bool(set(password) & set(password.upper()))
    has_special = bool(set(password) & set('!"§$%&/()=?'))

    return length_ok and has_number and has_lower and has_upper and has_special

  
class ValidateTests(unittest.TestCase):

    def test_empty(self):
        self.assertFalse(validate(''))

    def test_too_short(self):
        self.assertFalse(validate('aAbB1!?'))

    def test_too_long(self):
        self.assertFalse(validate('aA1!?' * 4 + 'a'))

    def test_no_number(self):
        self.assertFalse(validate("aAbBcC!?"))

    def test_no_upper(self):
        self.assertFalse(validate("aabbzz()"))

    def test_no_lower(self):
        self.assertFalse(validate("%&AABBCC"))

    def test_no_special(self):
        self.assertFalse(validate("aAbmMC19"))

    def test_valid(self):
        self.assertTrue(validate("a1?mzuF4"))


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