by Stephen Ng and Noel Yap

Old habits die hard. Particularly when it comes to testing--once you get used to working in a project blanketed with lots of fast-running unit tests, it's hard to go back.

So when some of us at Google learned that we weren't able to use our favorite mocking libraries when writing for our favorite mobile platform (Android, naturally), we decided to do something about it.

As many of you already know (since you read this blog), mocking combined with dependency injection is a valuable technique for helping you write small, focused unit tests. And those tests in turn can help you structure your code so that it's loosely coupled, making it more readable and maintainable.

With a bit of setup, this can be done in Android, too. We've put together a tutorial describing our approach. It's the first installment in what we hope will be a series of articles on android app development and testing, from the perspective of Googlers who are not actually on the Android team. We'd love to hear whether you find it useful.