import unittest

def is_it_prime(n):
    if n < 2:
        return False
    for b in range(2, int(n ** 0.5) + 1):
        if n % b == 0:
            return False
    return True

class TestPrimeFunction(unittest.TestCase):
    def test_prime_numbers(self):
        self.assertTrue(is_it_prime(2))
        self.assertTrue(is_it_prime(3))
        self.assertTrue(is_it_prime(5))
        self.assertTrue(is_it_prime(7))
        self.assertTrue(is_it_prime(11))
    
    def test_non_prime_numbers(self):
        self.assertFalse(is_it_prime(1))
        self.assertFalse(is_it_prime(4))
        self.assertFalse(is_it_prime(6))
        self.assertFalse(is_it_prime(8))
        self.assertFalse(is_it_prime(9))
    
    def test_large_prime(self):
        self.assertTrue(is_it_prime(101))
    
    def test_large_non_prime(self):
        self.assertFalse(is_it_prime(100))
    
    def test_negative_numbers(self):
        self.assertFalse(is_it_prime(-1))
        self.assertFalse(is_it_prime(-10))
        self.assertFalse(is_it_prime(-17))

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