A Data Flow Analysis Framework for Data Flow Subsumption
This work addresses the high expense of data flow testing for software testers by providing a formal framework to eliminate redundant test requirements, though it appears incremental in nature.
The paper tackles the problem of reducing the cost of data flow testing by addressing redundant definition-use associations through subsumption, presenting a formal Data Flow Subsumption Framework (DSF) and an algorithm to efficiently identify non-subsumed associations.
Data flow testing creates test requirements as definition-use (DU) associations, where a definition is a program location that assigns a value to a variable and a use is a location where that value is accessed. Data flow testing is expensive, largely because of the number of test requirements. Luckily, many DU-associations are redundant in the sense that if one test requirement (e.g., node, edge, DU-association) is covered, other DU-associations are guaranteed to also be covered. This relationship is called subsumption. Thus, testers can save resources by only covering DU-associations that are not subsumed by other testing requirements. In this work, we formally describe the Data Flow Subsumption Framework (DSF) conceived to tackle the data flow subsumption problem. We show that DFS is a distributive data flow analysis framework which allows efficient iterative algorithms to find the Meet-Over-All-Paths (MOP) solution for DSF transfer functions. The MOP solution implies that the results at a point $p$ are valid for all paths that reach $p$. We also present an algorithm, called Subsumption Algorithm (SA), that uses DSF transfer functions and iterative algorithms to find the local DU-associations-node subsumption; that is, the set of DU-associations that are covered whenever a node $n$ is toured by a test. A proof of SA's correctness is presented and its complexity is analyzed.