Foundations of Software Testing: Fundamental Algorithms and Techniques

Test Adequacy Assessment

7.6.2 THE COUPLING EFFECT

While the CPH arises out of observations of programmer behavior, the

coupling effect is observed empirically. The coupling effect has been

paraphrased by DeMillo, Lipton, and Sayward as follows:

Test data that distinguishes all programs differing from a correct one by only

simple errors is so sensitive that it also implicitly distinguishes more complex

errors.

Stated alternately, again in the words of DeMillo, Lipton and Sayward

“. . . seemingly simple tests can be quite sensitive via the coupling effect.”

As explained earlier, a seemingly simple first-order mutant could be ei-

ther equivalent to its parent or not. For some input, a nonequivalent

mutant forces a slight perturbation in the state space of ...