Summary
Unit testing is a practice for verifying individual functions or methods in isolation using test cases and assertions to ensure they behave as expected under various conditions. It helps catch bugs early, document code behavior, and supports safe refactoring.

General domain of usage
software development

Unit testing is a software testing practice that verifies individual units of code, such as functions or methods, to ensure they behave as intended and produce correct results.


Definition

Watch this quick video summary to reinforce your understanding of unit testing. You'll see how unit tests check individual functions or methods for correct behavior, why early bug detection matters, and how unit testing supports code quality and confidence. This visual recap helps you connect the main ideas and see unit testing in action.

Unit testing is a foundational software development practice that verifies individual units of code, such as functions or methods, in isolation to ensure they behave as expected and help catch issues early.

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In this example, you see a simple function, `add`, that returns the sum of two numbers. The unit test class, `TestAddFunction`, contains a method that checks if `add(2, 3)` correctly returns `5`. This illustrates how unit testing verifies that individual pieces of code behave as intended, catching mistakes quickly and reliably.

What is the primary goal of unit testing?

Learn how to write reliable Python code by testing it the right way. This short course introduces unit testing using Python’s built-in unittest framework, focusing on practical skills rather than theory. You’ll learn what unit tests are, why they matter, and how to write clear, meaningful tests for real Python functions. The course covers assertions, testing edge cases, handling exceptions, and understanding test failures. You’ll also learn how to structure test files and run tests confidently.

Get started with the basics of unit testing in Python. Learn what unit tests are, why they are important, and how they fit into the software development process.

Learn how to write clear and meaningful unit tests using assertions and by testing a variety of scenarios.

Discover how to test code that raises exceptions and how to interpret test failures.

Learn how to structure your test files and run tests efficiently.

What is Unit Testing?