Dynamic Impact Analysis: Analyzing Error Propagation In Program Executions

Test adequacy criteria serve as rules to determine whether a test set adequately tests a program. The e ectiveness of a test adequacy criterion is determined by its ability to detect faults. For a test case to detect a speci c fault, it should execute the fault, cause the fault to generate an erroneous state and propagate the error to the output. Analysis of previously proposed code-based testing strategies suggests that satisfying the error propagation condition is both important and expensive. The technique of dynamic impact analysis is proposed for analyzing a program execution and estimating the error propagation behavior of various potential sources of errors in the execution. Impact graphs are introduced to provide an infrastructure supporting the analysis. A program impact graph modi es the notion of a program dependence graph proposed in the literature in order to capture some of the subtle impact relationships that exist in a program. An execution impact graph represents the dynamic impact relationships that are demonstrated during a program execution. The notion of impact strength is de ned as a quantitative measure of the error sensitivity of an impact. A cost-e ective algorithm for analyzing impact relationships in an execution and computing the impact strengths is presented. A research prototype implemented to demonstrate the feasibility of dynamic impact analysis is brie y described. The time complexity of dynamic impact analysis is shown to be linear with respect to the original execution time, and experimental measurements indicate that the constant of proportionality is a small number.