# Example of a test case using unittest        
import unittest

def add_numbers(a, b):
    return a + b

class TestAddNumbers(unittest.TestCase):
    def test_add_positive_numbers(self):
        result = add_numbers(5, 3)
        self.assertEqual(result, 8)

    def test_add_negative_numbers(self):
        result = add_numbers(-5, -3)
        self.assertEqual(result, -8)

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