import unittest
import sys


def is_prime(n):
    """Checks if a number is prime."""
    if not isinstance(n, int) or n <= 1:
        return False
    for i in range(2, int(n**0.5) + 1):
        if n % i == 0:
            return False
    return True


def sum_of_first_n_primes(n):
    """Calculates the sum of the first n prime numbers."""
    if not isinstance(n, int) or n <= 0:
        return 0
    count = 0
    num = 2
    prime_sum = 0
    while count < n:
        if is_prime(num):
            prime_sum += num
            count += 1
        num += 1
    return prime_sum


class TestPrimeFunctions(unittest.TestCase):

    def test_is_prime_small_primes(self):
        self.assertTrue(is_prime(2))
        self.assertTrue(is_prime(3))
        self.assertTrue(is_prime(5))
        self.assertTrue(is_prime(7))
        self.assertTrue(is_prime(11))

    def test_is_prime_small_composites(self):
        self.assertFalse(is_prime(1))
        self.assertFalse(is_prime(4))
        self.assertFalse(is_prime(6))
        self.assertFalse(is_prime(8))
        self.assertFalse(is_prime(9))

    def test_is_prime_edge_cases(self):
        self.assertFalse(is_prime(0))
        self.assertFalse(is_prime(-1))
        self.assertTrue(is_prime(101))

    def test_sum_of_first_n_primes_small_n(self):
        self.assertEqual(sum_of_first_n_primes(1), 2)
        self.assertEqual(sum_of_first_n_primes(2), 5)
        self.assertEqual(sum_of_first_n_primes(3), 10)
        self.assertEqual(sum_of_first_n_primes(4), 17)
        self.assertEqual(sum_of_first_n_primes(5), 28)

    def test_sum_of_first_n_primes_zero_n(self):
        self.assertEqual(sum_of_first_n_primes(0), 0)

    def test_sum_of_first_n_primes_larger_n(self):
        self.assertEqual(sum_of_first_n_primes(10), 129)

    def test_sum_of_first_n_primes_none(self):
        self.assertEqual(sum_of_first_n_primes(None), 0)

    def test_is_prime_none(self):
        self.assertEqual(is_prime(None), False)

    def test_sum_of_first_n_primes_string(self):
        self.assertEqual(sum_of_first_n_primes(''), 0)

    def test_is_prime_string(self):
        self.assertEqual(is_prime(''), False)

    def test_sum_of_first_n_primes_boolean(self):
        self.assertEqual(sum_of_first_n_primes(False), 0)

    def test_is_prime_boolean(self):
        self.assertEqual(is_prime(False), False)


class CustomTestResult(unittest.TestResult):
    def __init__(self, stream):
        super().__init__()
        self.stream = stream

    def addSuccess(self, test):
        self.stream.write("*** test_passed ***\n")

    def addFailure(self, test, err):
        self.stream.write("*** assertion_failed ***\n")

    def addError(self, test, err):
        error_message = str(err[1])
        self.stream.write(
            f"*** exception_raised ***, error message: {error_message}\n")


class CustomTestRunner(unittest.TextTestRunner):
    def run(self, test):
        result = CustomTestResult(self.stream)
        test(result)
        return result


if __name__ == '__main__':
    suite = unittest.TestLoader().loadTestsFromTestCase(TestPrimeFunctions)
    runner = CustomTestRunner(stream=sys.stdout)
    runner.run(suite)