Have you ever been in a long flight and have seen the stuffs attached to the back of the seat in front of you? One is used to place the food trays they serve for breakfast, lunch or dinner. Another -at the eyes level- is used to display information.

Now, let’s assume we don’t know what that stuff is for. We could get rid of all that stuff and test the plane to see if it flies. After confirming that the plane flies just fine without all that removed stuff, the airline starts to notice an increasing loss of passengers to other airlines that still have that “junk” attached to the back of the seats in long flights. That’s a surprisingly unexpected result, isn’t it? 🙂

Another way to look at this is by playing loud rock music to a crab dancing on a table. As we remove the crab legs one at a time we notice that the crab starts missing the rhythm and slows down considerably. After removing the last leg the crab stops dancing completely. Conclusion: the crab got completely deaf, hence its legs are associated with the hearing system. 🙂

Testing functionality is not a joke. It’s a serious task that must be done carefully and with open mind.