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Robotium is an open source testing framework for Android applications. It makes it easy to write complex black-box test cases. Test driven development is a methology where tests are written before the actual application.
1. Write a testcase
2. Watch it failing
3. Write the actual source code in you application which enables the test to pass
4. Watch the test passing
5. Go back to step 1
The following video gives you an introduction into Robotium:
I will definitely use Robotium for my future Android projects. It is really worth having a look at it.
There is another interersting video: