What is meant by 'mocking' in software testing?

Mocking in software testing refers to the practice of simulating real objects in order to test the functionality of a specific component or module in isolation. This technique allows developers to create 'mock' versions of objects, which imitate the behavior of real objects without relying on their actual implementations. By using mocks, testers can focus on the component being tested without the complexities or dependencies that other objects might introduce during the testing process.

For example, if a module relies on a database connection, mocking would allow the developer to simulate the database interaction without needing to connect to a real database. This helps in accurately testing the module under specific conditions and ensuring that it behaves as expected when interacting with those simulated objects. This form of testing can lead to more efficient and reliable unit tests, as it removes external dependencies and potential points of failure.

The other options describe different concepts that, while relevant to software development and testing, do not encapsulate the essence of mocking. For instance, optimizing code performance is about improving its efficiency, documenting code focuses on creating clear explanations for the existing code, and debugging involves identifying and fixing errors in the code. None of these directly relate to the concept of simulating objects for testing purposes, which is the foundation of mocking in software engineering.