It’s frustrating when you receive materials into test that are quickly found to be unfit for purpose. Frustrating and wasteful of the time of everybody concerned. Frustrating, wasteful of time and almost certainly destined to cause bad feeling somewhere along the line. Frustrating, wasteful of time, destined to cause bad feeling and, well, I’m sure you can fill in the rest from your own experience.

The Riddle of Testing is not why does this keep happening? (although that could easily be the Second Riddle of Testing and its answers are many and varied). No, the Riddle of Testing is a coarse filter you knocked up quickly out of old chicken wire and a crate last time around, and you keep in your shed.

You’ll surely have a few of them, in different shapes and sizes, and when new material arrives you chuck it into one and shake it – sometimes by hand but sometimes you’ll have jury-rigged an old motor to wobble the thing for you. If there’s any lumps left on top then you inspect them first, with a stopping strategy in mind.

Your riddle is a quick validity checker and when you find you’re employing it frequently, you’ll wonder whether you could work with your colleagues to deploy it upstream so that next time round you can contemplate your surgical equipment rather than your gardening tools and they can sit down for five minutes and a cuppa after delivery.