One of the Twitter testing community, @JariLaakso, posted this question:
Two trains are going to crash. Brakes don’t work. What would you do?
Of course, you can’t answer this without asking a lot of questions to establish context.
- Are you on board one of the trains? If so, are you a passenger or a member of the train crew? If train crew, are you in the driving cab, or elsewhere on the train?
- Is your train actually moving, or is it stationary and about to be hit by the other train?
- If you’re not on board the train, are you a bystander, or someone like a signaller?
- How long before the collision? Just seconds, or longer than that?
- Is there anyone on board the trains at all? Perhaps it’s a staged crash for a film?
- Is the “crash” even an impending collision? Or is it a case of software gone blue-screen-of-death meaning the brakes can’t be released and the train needs rebooting before it can go anywhere? This may sound silly, but I’ve been on a Virgin Trains Pendolino that had to do precisely that.
The actual answer turned out to be none of those things, but that’s not really the point. It’s about asking the right questions to get the information you need to be able to answer the original question “What do you do?”.
As an aside, real-life rail (or air) accident reports can often be worthwhile reading for a tester. I’m not talking about sensationalist reports of death and destruction, but the technical stories behind the accidents and how they occurred.
I remember reading L.T.C.Rolt’s classic “Red For Danger” at a formative age. It’s a very well-written and readable account of the evolution of railway safety throughout the steam age. It starts with the development of early primitive signalling systems from the 1840s onwards, and tells of the lessons learned from each successive serious accident. As the story moves into the 20th century, increasingly sophisticated systems from signal interlocking to better and stronger rolling stock meant far fewer disastrous accidents. But even the best systems can fail, with sometimes fatal consequences, and the book explains how.
It’s essentially the story of bugs.