Assisting in fault localization using visual programming constructs

Locating variable definition use interactions (du-chains) that are associated with program faults is one of the most difficult and time-consuming task of the intraprocedural testing/debugging process. This task is further complicated by the presence of loops and aliases. To locate faults associated with untraversed du-chains, developers must identify suspicious variables, statements, controls and loop paths involved in failures. This paper presents a new technique that uses visualization to assist with these tasks. The technique employs a mapping scheme that uses visual artifacts and colors to visually map the participation of each statement, control, and variable du-chains, in the outcome of the execution of a procedure. Using our visual mapping technique, a user can inspect the colored artifacts, and identify, in addition to predicate and non-predicate statements, du-chains involved in failures, and potentially locate program faults. The paper also describes a prototype tool that implements our visual testing technique, along with a set of an empirical study that we have used to evaluate the error detection capability of our technique. The results of the subject we studied show that the technique can be effective in helping a user locate faults that are associated with untraversed statements, controls, and above all du-chains, in a procedure under test.