Posts Tagged ‘embedded’


Thanks testedtested about good thoughts @Twitter. 🙂 I had to start thinking about testability and its relationship with customer happiness and usability. 140 characters is too less for very well formulated ideas and comments so I had to write blog entry.

If I can use application, it doesn’t mean that I can test it. In many cases the testers must request developers to add code and features to increase testability. In many applications good usability means better testability, but that’s not case in many embedded systems.

Good example is Google’s self-driving car. From user point of view it is very simple system. Just submit where you are going to, hit the button and car takes you there. (This is very simplified view.) Even if that process is done simple, it is definitely not the same as testability.

I slice the simplified system to multiple parts:

  • Sensors
  • Motor
  • Wheel
  • User’s GUI which inputs the destination
  • Button which starts to drive

The software which controls all of these is software under testing (SUT) in my example. For me I’d need following things this to be testable:

  • I have to be able to send artificial messages from the sensors to SUT
  • I have to be able to inspect what kind of messages motors get
  • I have to be able to give artificial feedback from motor to SUT
  • I have to be able to control (virtual) wheels same way as normal road affects to wheels

If any of these is missing, I would not be able to test the control system. These need plenty of simulators and stubs which tester or test automation can inspect and control. But even without those simulators and stubs, extra interfaces the user could use the system and even be happy (if it works as expected). And even tester could use the system without them.

So testability is not always automatically part of usable software. Sometimes testability needs plenty of additional work for developers. And in those cases it is usually testers’ responsibility to give details how to make application more testable.