Test doubles are substitutes for components in software testing, used to isolate a unit of code from its dependencies to achieve controlled and deterministic test conditions. They emulate the behavior of real components, ensuring the test focuses only on the unit under examination. The term "test double" encompasses various specific types:

Dummy

Implementation or replica of another object for having an entity of the same type as the original. It doesn't have any logic and their methods return null. They are usually used to fill functions' parameters list and are never actually used.

ValidateAuthDummy { authorize($user) { return null; } }