Mocking

Mocking is a software testing technique that involves creating simulated objects, known as mocks, to replace real dependencies in a system during testing. It allows developers to isolate the unit under test by controlling the behavior of external components, such as APIs, databases, or services, ensuring tests focus on specific logic without side effects. This helps verify interactions and improve test reliability by eliminating unpredictable external factors.

Also known as: Mock objects, Test doubles, Fakes, Stubs, Mocks

Why learn Mocking?

Developers should use mocking when writing unit tests to isolate code from external dependencies, enabling faster and more deterministic tests that don't rely on network calls, databases, or third-party services. It's particularly useful in test-driven development (TDD) and continuous integration pipelines to ensure code quality and catch bugs early, such as when testing API integrations or complex business logic without actual data sources.

Learning Resources

• docs: Martin Fowler - Mocks Aren't Stubs
• docs: Mockito Documentation
• tutorial: Unit Testing with Mocks - FreeCodeCamp
• tutorial: Mocking in Python with unittest.mock - Real Python
• docs: Test Doubles - xUnit Patterns