Have you dealt with writing and executing unit tests in your projects?

Yes, in Python projects I have written and executed unit tests using tools such as unittest and pytest.

Unit tests allow you to verify the correctness of individual functions or classes.

Here's a simple example of a test using unittest:

import unittest

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

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

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

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

This approach helps identify errors early in development and maintain code quality.