Enumerating message paths for interaction testing of object-oriented systems

Abstract

MM path is integration artifact of object-oriented systems and is characterized by interleaved sequence of messages and method execution paths. In the context of UML sequence diagrams, an MM path is usually found common in many message paths and concatenation of one MM path with different MM paths results in distinct message paths. Adequate testing of all message paths in UML sequence diagrams implies the coverage of all possible concatenation of constituent MM paths in different object-states, which may not be fully achieved in practical situations. With limited test effort, practitioners are compelled to consider a subset of all message paths in ad-hoc manner or priority basis. It can be possible that the selected paths may not include at least one instance of highly critical MM path, whereas less critical MM paths may have been included with multiple instances. It is, therefore, necessary that the selected message paths would contain one instance of all MM paths and their additional instances as per their priorities. To address this problem, we propose two coverage criteria: all MM paths and prioritized MM paths and an MM path-based coverage model. To obtain such coverage model, we build a graph model called as sequence integration graph from the sequence diagram and thereafter, synthesize MM paths to merge them into a set of connected trees. Further, we capture priority information of the MM paths by means of edge weights and order of concatenation among the MM paths by means of connector edges between the trees. These information captured in the MM coverage model helps to determine effective coverage of the MM paths. Our experimental results substantiate usefulness of our MM path-based coverage model for selecting message paths to satisfy all MM paths and prioritized MM paths coverage criteria in the context of integration testing of object-oriented systems with the limited testing effort.