Googletest Mocking (gMock) Framework

Google's framework for writing and using C++ mock classes. It can help you derive better designs of your system and write better tests.

It is inspired by:

It is designed with C++'s specifics in mind.

gMock:

Provides a declarative syntax for defining mocks.
Can define partial (hybrid) mocks, which are a cross of real and mock objects.
Handles functions of arbitrary types and overloaded functions.
Comes with a rich set of matchers for validating function arguments.
Uses an intuitive syntax for controlling the behavior of a mock.
Does automatic verification of expectations (no record-and-replay needed).
Allows arbitrary (partial) ordering constraints on function calls to be expressed.
Lets a user extend it by defining new matchers and actions.
Does not use exceptions.
Is easy to learn and use.

Details and examples can be found here:

GoogleMock is a part of GoogleTest C++ testing framework and a subject to the same requirements.