primes.py

# primes.py

from math import sqrt


def find_next_prime(n):
    n = int(n)      # Allows for floating point inputs
    if n < 2:
        return 2    # Primes are natural numbers, 2 is the smallest possible
    while True:
        n += 1
        for i in range(2, int(sqrt(n))):
            if n % i == 0:
                break
        else:
            return n

###############################################################
# primes_test.py

#!/usr/bin/env python3

import unittest
from primes import find_next_prime


class PrimesTest(unittest.TestCase):
    def test_next_6(self):
        self.assertEqual(find_next_prime(6), 7)

    def test_next_after_prime(self):
        self.assertEqual(find_next_prime(11), 13)

    def test_negative_input(self):
        self.assertEqual(find_next_prime(-1234), 2)

    def test_float_input(self):
        self.assertEqual(find_next_prime(6.5), 7)

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