We have seen the mock objects provided by the Android testing framework in Chapter 1, Getting Started with Testing, and evaluated the concerns about not using real objects to isolate our tests from the surrounding environment.
The next chapter deals with Test-driven Development, and if we were Test-driven Development purists, we can argue about the use of mock objects and be more inclined to use real ones. Martin Fowler calls these two styles the classical and mockist Test-driven Development dichotomy in his great article Mocks aren't stubs, which can be read online at http://www.martinfowler.com/articles/mocksArentStubs.html.
Independent of this discussion, we are introducing mock objects as one of the available building blocks because, sometimes, using mock objects in our tests is recommended, desirable, useful, or even unavoidable.
The Android SDK provides the following classes in the subpackage android.test.mock to help us: