How can you implement testing of individual components of your code to verify their correctness?

To test individual components of code in Python, the unittest module or third-party libraries like pytest are usually used. The main idea is to write tests that verify the correctness of functions or classes with different input data.

Example using unittest:

import unittest

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

class TestAddFunction(unittest.TestCase):
    def test_positive_numbers(self):
        self.assertEqual(add(2, 3), 5)

    def test_negative_numbers(self):
        self.assertEqual(add(-1, -1), -2)

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

This approach allows automating checks, quickly identifying errors when code changes, and maintaining project quality.