Python/maths/prime_check.py
2019-07-11 11:16:42 +02:00

58 lines
1.7 KiB
Python

"""Prime Check."""
import math
import unittest
def prime_check(number):
"""
Check to See if a Number is Prime.
A number is prime if it has exactly two dividers: 1 and itself.
"""
if number < 2:
# Negatives, 0 and 1 are not primes
return False
if number < 4:
# 2 and 3 are primes
return True
if number % 2 == 0:
# Even values are not primes
return False
# Except 2, all primes are odd. If any odd value divide
# the number, then that number is not prime.
odd_numbers = range(3, int(math.sqrt(number)) + 1, 2)
return not any(number % i == 0 for i in odd_numbers)
class Test(unittest.TestCase):
def test_primes(self):
self.assertTrue(prime_check(2))
self.assertTrue(prime_check(3))
self.assertTrue(prime_check(5))
self.assertTrue(prime_check(7))
self.assertTrue(prime_check(11))
self.assertTrue(prime_check(13))
self.assertTrue(prime_check(17))
self.assertTrue(prime_check(19))
self.assertTrue(prime_check(23))
self.assertTrue(prime_check(29))
def test_not_primes(self):
self.assertFalse(prime_check(-19),
"Negative numbers are not prime.")
self.assertFalse(prime_check(0),
"Zero doesn't have any divider, primes must have two")
self.assertFalse(prime_check(1),
"One just have 1 divider, primes must have two.")
self.assertFalse(prime_check(2 * 2))
self.assertFalse(prime_check(2 * 3))
self.assertFalse(prime_check(3 * 3))
self.assertFalse(prime_check(3 * 5))
self.assertFalse(prime_check(3 * 5 * 7))
if __name__ == '__main__':
unittest.main()