I'm teaching a capstone (the final class in an undergraduate program) software engineering course in which we are developing Android applications in Java. I consider test-driven development and unit testing important but am having trouble coming up with Android-related assignments, since so much mobile programming is about user interfaces and synchronization, neither of which are ideal for unit testing.
The only thing I've thought of is that they could unit test a database running on Android, which would also let me introduce mocking, but that doesn't sound very interesting.
Any suggestions of a small but interesting Android project suitable to TDD and unit testing?