The topic tries to cover high level of Test Doubles, Mocks. Here we have many named concepts around, Fake, Mock, Spy, Stub, etc…
Testing with mocks, stubs is primarily happens with unit, integration testing.
In object oriented world, bigger or smaller units of codes are tested, and while we having SRP objects, we still have to deal with dependencies and other object structures while we processing code.
To clean cut and provide a stable state we’re should fix those parameters/dependencies, which are not in the question from the testing perspective.