Test requirement examples
Suppose we are given the enviable task of testing bags of jelly beans. We need to come up with ways to sample from the bags. Suppose these jelly beans have the following six flavors and come in four colors: Lemon (colored Yellow), Pistachio (Green), Cantaloupe (Orange), Pear (White), Tangerine (also Orange), and Apricot (also Yellow). A simple approach to testing might be to test one jelly bean of each flavor. Then we have six test requirements, one for each flavor. We satisfy the test requirement "Lemon" by selecting and, of course, tasting a Lemon jelly bean from a bag of jelly beans. The reader might wish to ponder how to decide, prior to the tasting step, if a given Yellow jelly bean is Lemon or Apricot. This dilemma illustrates a classic controllability issue.