Using a mocking framework can facilitate a smooth unit testing experience, especially when unit testing a portion of code with dependencies in which mock objects are created and substituted for the dependencies. While it is easier using mocking frameworks, you might sometimes prefer to hand-roll mock objects for your unit tests and not add extra complexity or additional libraries to your project or code base.
Hand-rolled mocks are classes that are created for the purpose of testing and used to replace production objects. These created classes will have equivalent methods as the production classes with the same definitions and return values to effectively simulate the production classes and to use as substitute for dependencies in unit tests.