What is the purpose and role of stubs in the testing process?

Stubs in unit testing are simplified replacements for real dependencies of the tested module, which return predefined data. This allows isolating the code under test from external factors and focusing on verifying its logic.

Role of stubs:

• Isolate the tested component from complex or unstable dependencies (e.g., databases, network services).
• Speed up tests by avoiding real calls.
• Control the behavior of dependencies to test different scenarios.

Example: if a function depends on an API, a stub can return a fixed response to test how the code handles it.