Can you explain what is meant by modular testing in software development?

Unit testing is the process of verifying individual parts of a program (modules) for correctness. Each module is tested in isolation to ensure it performs its function correctly.

Goals of unit testing:

• Detect errors early in development.
• Ensure stability and quality of the code.
• Simplify debugging and maintenance.

In Python, the built-in unittest module is often used for unit testing. Here's a simple test example:

import unittest

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

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

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

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

This approach helps ensure that individual parts of the program work as intended and facilitates their integration into larger systems.