Complete interaction testing of components is too costly in all but the smallest systems. Yet component interactions are likely to cause unexpected faults. Recently, design of experiment techniques have been applied to software testing to guarantee a minimum coverage of all t-way interactions across components. However, t is always fixed. This paper examines the need to vary the size of t in an individual test suite and defines a new object, the variable strength covering array that has this property. We present some computational methods to find variable strength arrays and provide initial bounds for a group of these objects.

Software system faults are often caused by unexpected interactions among components. Yet the size of a test suite required to test all possible combinations of interactions can be prohibitive in even a moderately sized project. Instead, we may use pairwise or t-way testing to provide a guarantee that all pairs or t-way combinations of components are tested together This concept draws on methods used in statistical testing for manufacturing and has been extended to software system testing. A covering array, CA(N; t, k, v), is an N/spl times/k array on v symbols such that every N x t sub-array contains all ordered subsets from v symbols of size t at least once. The properties of these objects, however do not necessarily satisfy real software testing needs. Instead we examine a less studied object, the mixed level covering array and propose a new object, the variable strength covering array, which provides a more robust environment for software interaction testing. Initial results are presented suggesting that heuristic search techniques are more effective than some of the known greedy methods for finding smaller sized test suites. We present a discussion of an integrated approach for finding covering arrays and discuss how application of these techniques can be used to construct variable strength arrays.

Developers need tool support to help manage the wide range of inconsistencies that occur during software development. Such tools need to provide developers with ways to define, detect, record, present, interact with, monitor and resolve complex inconsistencies between different views of software artifacts, different developers and different phases of software development. This paper describes our experience with building complex multiple-view software development tools that support diverse inconsistency management facilities. We describe software architectures that we have developed and user interface techniques that are used in our multiple-view development tools, and we discuss the effectiveness of our approaches compared to other architectural and HCI techniques.

A new software architecture for supporting inter-object consistency management is described. Objects with interdependent data values are kept consistent by propagating descriptions of object state changes along inter-object relationships. Response to and storage of these change descriptions supports the implementation of consistency management techniques in a more homogeneous way than existing models. Such techniques include efficient attribute recalculation and constraint schemes, multiple view consistency, and undo-redo, versioning and cooperative work facilities. Applications of the new architecture to user interface, graphical editor and programming environment construction are described.