Most often defect information is used to make judgment of quality. We use the rate of arrival. If the number of defects found decrease with time, we infer that the quality is improving. Let us deliberate upon this. Defects become visible when failures are noticed, which are the result of latent fault(s). And this happens when we ‘sweep’ the system with a set of inputs i.e. test-cases. And if we have not covered the important areas of the software equivalent to ‘sweeping the room’, then we may not surface these defects. And therefore no ‘glass shards’, until it pokes us – Ouch.
In the May 2014 issue of Tea-time with Testers, ezine, T Ashok narrates a personal story as analogy to drive home the point in the article – The shattered tube light. Read below the full article: