import unittest
from count_primes import count_primes


class TestCountPrimes(unittest.TestCase):
    def test_zero(self):
        self.assertEqual(count_primes(0), 0)

    def test_one(self):
        self.assertEqual(count_primes(1), 0)

    def test_two(self):
        self.assertEqual(count_primes(2), 1)

    def test_ten(self):
        # Primes <= 10: 2, 3, 5, 7
        self.assertEqual(count_primes(10), 4)

    def test_hundred(self):
        # 25 primes <= 100
        self.assertEqual(count_primes(100), 25)


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