Efficient coverage testing using global dominator graphs

Abstract

Coverage testing techniques, such as statement and decision coverage, play a significant role in improving the quality of software systems. Constructing a thorough set of tests that yield high coverage, however, is often a very tedious, time consuming task. In this paper we present a technique to find a small subset of a program's statements and decisions with the property that covering the subset implies covering the rest. We introduce the notion of a mega block which is a set of basic blocks spanning multiple procedures with the property that one basic block in it is executed iff every basic block in it is executed. We also present an algorithm to construct a data structure called the global dominator graph showing dominator relationships among mega blocks. A tester only needs to create test cases that are aimed at executing one basic block from each of the leaf nodes in this directed acyclic graph. Every other basic block in the program will automatically be covered by the same test set.