The Revealing Power of a Test Case

\Propagation, infection, and execution analysis" (termed PIE) is used for predicting where faults can more easily hide in software. To make such predictions, programs are dynamically executed with test cases. In this paper, we collect information concerning those test cases into a histogram. Each bin in a histogram represents a single test case. The score in a bin predicts the likelihood that the test case will reveal a fault through the production of a failure (if a fault exists in the set of program locations that the test case executes). Preliminary experiments using program mutations suggest that the histogram technique presented in this paper can rank test cases according to their fault revealing ability.