This kata is an implementation of the Device Driver Kata by Emily Bache. In difference to Emily's kata this kata already contains the production code and focuses solely on getting the existing code under test using test doubles usually called "mocks".
The Java production code is based on Héctor Hugo Barriuso Matas solution.
Create unit tests for all functions of the DeviceDriver class. Make sure it is tested in isolation.
To measure your progress you should use code coverage tools.