A program correctness checker is an algorithm for checking the output of a computation. That is, given a program and an instance on which the program is run, the checker certifies whether the output of the program on that instance is correct. This paper defines the concept of a program checker. It designs program checkers for a few specific and carefully chosen problems in the class FP of functions computable in polynomial time. Problems in FP for which checkers are presented in this paper include Sorting, Matrix Rank and GCD. It also applies methods of modern cryptography, especially the idea of a probabilistic interactive proof, to the design of program checkers for group theoretic computations. Two strucural theorems are proven here. One is a characterization of problems that can be checked. The other theorem establishes equivalence classes of problems such that whenever one problem in a class is checkable, all problems in the class are checkable. Supported by NSF Grant #CCR88-136...

Objective measurement of test quality is one of the key issues in software testing. It has been a major research focus for the last two decades. Many test criteria have been proposed and studied for this purpose. Various kinds of rationales have been presented in support of one criterion or another. We survey the research work in

Where the creation, understanding, and assessment of software testing and regression testing techniques are concerned, controlled experimentation is an indispensable research methodology. Obtaining the infrastructure necessary to support such experimentation, however, is difficult and expensive. As a result, progress in experimentation with testing techniques has been slow, and empirical data on the costs and effectiveness of techniques remains relatively scarce. To help address this problem, we have been designing and constructing infrastructure to support controlled experimentation with testing and regression testing techniques. This paper reports on the challenges faced by researchers experimenting with testing techniques, including those that inform the design of our infrastructure. The paper then describes the infrastructure that we are creating in response to these challenges, and that we are now making available to other researchers, and discusses the impact that this infrastructure has and can be expected to have.

We present a general model of software development environments that consists of three components: structures, mechanisms and policies. The advantage of this model is that it distinguishes intuitively those aspects of an environment that are useful in comparing and contrasting software development environments. Our initial application of the model is to characterize four classes of environments by means of a sociological metaphor based on scale: the individual, the family, the city and the state models. The utility of the IFCS taxonomy is that it delineates the important classes of interactions among software developers and exposes the ways in which current software development environments inadequately support the development of large systems. We demonstrate the generality of our model by also applying it to a previously published taxonomy that categorizes environments according to how they relate to four historical trends: language-centered, structure-oriented, toolkit and method-bas...

Types of code changes in an object oriented library are described. A formal model for capturing and inferencing on the changes to identify affected classes is described. The model consists of three types of diagrams: the object relation diagram (ORD), the block branch diagram (BBD), and the object state diagram (OSD). An ORD describes the inheritance, aggregation, and association relationships between the classes of a C++ library. A BBD describes the control structure and interfaces of a member function. And an OSD describes the state behavior of a class. Unlike in modeling, these diagrams are automatically generated from code and facilitate understanding and changing a C++ library. An OO software maintenance environment that implements the research result is described. Our experience with the environment prototype shows promising results.

Where the development, understanding, and assessment of software testing and regression testing techniques are concerned, controlled experimentation is an indispensable research methodology. Obtaining the infrastructure necessary to support rigorous controlled experimentation with testing techniques, however, is difficult and expensive. As a result, progress in experimentation with testing techniques has been slow, and empirical data on the costs and effectiveness of testing techniques remains relatively scarce. To help address this problem, we have been designing and constructing infrastructure to support controlled experimentation with software testing and regression testing techniques. This paper reports on the challenges faced by researchers experimenting with testing techniques, including those that inform the design of our infrastructure. The paper then describes the infrastructure that we are creating in response to these challenges, and that we are now making available to other researchers, and discusses the impact that this infrastructure has and can be expected to have on controlled experimentation with testing techniques.

One significant challenge in bringing the power of parallel machines to application programmers is providing them with a suite of software tools similar to the tools that sequential programmers currently utilize. In particular, automatic or semi-automatic testing tools for parallel programs are lacking. This paper describes our work in automatic generation of all-du-paths for testing parallel programs. Our goal is to demonstrate that, with some extension, sequential test data adequacy criteria are still applicable to parallel program testing. The concepts and algorithms in this paper have been incorporated as the foundation of our DELaware PArallel Software Testing Aid, della pasta. Keywords: parallel programming, testing tool, all-du-path coverage 1 Introduction Recent trends in computer architecture and computer networks suggest that parallelism will pervade workstations, personal computers, and network clusters, causing parallelism to become available to more than just the users ...

Software testing consumes a large percentage of total software development costs. Yet, it is still usually performed manually in a non rigorous fashion. While techniques, and limited automatic support, for the generation of test data from the actual code of the system under test have been well researched, test cases generation from a high level specification of the intended behaviour of the system being developed has hardly been addressed. In this thesis we present a rationale for using tests derived from high level formal specifications and then set to find an efficient technique for the generation of adequate test sets from specifications written in our study language, VDM-SL. In this work, we formalise the traditional high level partitioning technique used in a previously researched test cases generator prototype, and extend it to take the semantics of VDM-SL fully into account. We then discuss, and illustrate, the shortcomings of the technique as used, which results in too few test...

The goal of this paper is to examine the testing of object-oriented systems and to compare and contrast it with the testing of conventional programming language systems, with emphasis on fault-based testing. Conventional system testing, object-oriented system testing, and the application of conventional testing methods to object-oriented software will be examined, followed by a look at the differences between testing of conventional (procedural) software and the testing of objectoriented software. An examination of software faults (defects) will follow, with emphasis on developing a preliminary taxonomy of faults specific to object-oriented systems. Test strategy adequacy will be briefly presented. As a result of these examinations, a set of candidate testing methods for object-oriented programming systems will be identified.

In this thesis my aim is to examine the common ground between formal methods and testing, and the benefits the two fields bring to one another. All too often they are regarded as mutually exclusive approaches in the development of software systems. The thesis begins with an examination of the motivation behind software testing, a summary of its development over the past few decades, and a survey of existing techniques. This involves a detailed discussion of some of those techniques, and leads on to an extensive case study. The case study shows how the use of a formal specification enables an existing "partition" based testing method to be used with far greater precision, but also highlights some of the limitations of the partition based techniques. The thesis continues with a comprehensive look at the development of theoretical models of testing since the mid 1970's, and the way they have used successively more complex software models in order to be able to adequately describe suitable...