Test Doubles


Fake	A test double that has a "working" implementation of the class, but it's implemented in a way that makes it good for tests but unsuitable for production
Mock	A test double that tracks which of its methods were called. It then passes or fails a test depending on whether it's methods were called correctly.
Stub	A test double that includes no logic and only returns what you program it to return. A `StubTaskRepository` could be programmed to return certain combinations of tasks from `getTasks` for example.
Dummy	A test double that is passed around but not used, such as if you just need to provide it as a parameter. If you had a `DummyTaskRepository`, it would just implement the `TaskRepository` with no code in any of the methods.
Spy	A test double which also keeps tracks of some additional information; for example, if you made a `SpyTaskRepository`, it might keep track of the number of times the `addTask` method was called.

For more information on test doubles, check out this article.

The documentation has some great tips about using test doubles in Android.