The Impact of Software Evolution on Code Coverage Information

Many tools and techniques for addressing software maintenance problems rely on code coverage information. Often, this coverage information is gathered for a specific version of a software system, and then used to perform analyses on subsequent versions of that system without being recalculated. As a software system evolves, however, modifications to the software alter the software’s behavior on particular inputs, and code coverage information gathered on earlier versions of a program may not accurately reflect the coverage that would be obtained on later versions. This discrepancy may affect the success of analyses dependent on code coverage information. Despite the importance of coverage information in various analyses, in our search of the literature we find no studies specifically examining the impact of software evolution on code coverage information. Therefore, we conducted empirical studies to examine this impact. The results of our studies suggest that even relatively small modifications can greatly affect code coverage information, and that the degree of impact of change on coverage may be difficult to predict.

Helping End-User Programmers “Engineer” Dependable Software

Not long ago, most software was written by professional programmers, who could be presumed to have an interest in software engineering methodologies and in tools and techniques for improving software dependability. Today, however, a great deal of software is written not by professionals but by end-users, who create applications such as multimedia simulations, dynamic web pages, and spreadsheets. Applications such as these are often used to guide important decisions or aid in important tasks, and it is important that they be sufficiently dependable, but evidence shows that they frequently are not. For example, studies have shown that a large percentage of the spreadsheets created by end-users contain faults, and stories abound of spreadsheet faults that have led to multi-million dollar losses. Despite such evidence, until recently, relatively little research had been done to help end-users create more dependable software.

Using Source-Code Analysis to Help End-user Programmers Create Dependable Software

Not long ago, most software was written by professional programmers, who could be presumed to have an interest in software engineering methodologies and in tools and techniques for improving software dependability. Today, however, a great deal of software is written not by professionals but by end-users, who create applications such as multimedia simulations, dynamic web pages, and spreadsheets. Applications such as these are often used to guide important decisions or aid in important tasks, and it is important that they be sufficiently dependable, but evidence shows that they frequently are not. For example, studies have shown that a large percentage of the spreadsheets created by end-users contain faults. Despite such evidence, until recently, relatively little research had been done to help end-users create more dependable software. We have been working to address this problem by finding ways to provide at least some of the benefits of formal software engineering techniques to end-user programmers. In this talk, focusing on the spreadsheet application paradigm, I present several of our approaches, focusing on methodologies that utilize source-code-analysis techniques to help end-users build more dependable spreadsheets. Behind the scenes, our methodologies use static analyses such as dataflow analysis and slicing, together with dynamic analyses such as execution monitoring, to support user tasks such as validation and fault localization. I show how, to accommodate the user base of spreadsheet languages, an interface to these methodologies can be provided in a manner that does not require an understanding of the theory behind the analyses, yet supports the interactive, incremental process by which spreadsheets are created. Finally, I present empirical results gathered in the use of our methodologies that highlight several costs and benefits trade-offs, and many opportunities for future work.

Incorporating Varying Test Costs and Fault Severities into Test Case Prioritization

Test case prioritization techniques schedule test cases for regression testing in an order that increases their ability to meet some performance goal. One performance goal, rate offault detection, measures how quickly faults are detected within the testing process. In previous work we provided a metric, APFD, for measuring rate of fault detection, and techniques for prioritizing test cases to improve APFD, and reported the results of experiments using those techniques. This metric and these techniques, however, applied only in cases in which test costs and fault severity are uniform. In this paper, we present a new metric for assessing the rate of fault detection of prioritized test cases, that incorporates varying test case and fault costs. We present the results of a case study illustrating the application of the metric. This study raises several practical questions that might arise in applying test case prioritization; we discuss how practitioners could go about answering these questions.

Taking an Endemically Infected Bovine Tb Area Through to Livestock Clearance. A Case Study of West Taupo, New Zealand

The Pest Management Strategy for Bovine Tuberculosis (Tb) in New Zealand aims to achieve efficient freedom from Tb by 2013 and to eradicate the disease from livestock and wildlife. The West Taupo area, in the central North Island of New Zealand, was chronically infected with Tb in both domestic livestock herds (cattle and deer) and within wildlife populations (brushtail possum, ferret, feral deer and pigs). Through the development and implementation of a technically innovative management plan, this area is now approaching Tb free status. The case study / management plan reported here discusses the operational techniques and strategies that were implemented to achieve Tb clearance in the livestock herds and the possibilities of eradication from wildlife species. It particularly identifies the variations in control strategies that are required as population densities reduce and the challenges of maintaining strong effective control at low densities of some wildlife species, whilst not needing to control other species that were initially clinically diagnosed with Tb control. Use of diagnostic tools and education as an area moves through the cycle towards Tb freedom are as essential as the physical control activities. The use of intensive monitoring of both livestock and wildlife species as trend and performance indicators and the need to educate farmers, hunters and other land use groups become increasingly important.

THE HANDBOOK OF WILDLIFE DEPREDATION TECHNIQUES: A SYNOPSIS

In 1979, the Game Division Administration of the Wyoming Game and Fish Department (WGFD) appointed John Demaree and Tim Fagan to develop a handbook that would address the ever increasing problem of wildlife depredation. Field personnel were often times at a loss on how to deal with or evaluate the assorted types of damage situations they were encountering. Because Wyoming requires landowners to be reimbursed for damage done by big and trophy game and game birds to their crops and livestock, an evaluation and techniques handbook was desperately needed. The initial handbook, completed in January 1981, was 74 pages, and both John and I considered it a masterpiece. It did not take long, however, for this handbook to become somewhat lacking in information and outdated. In 1990, our administration approached us again asking this time for an update of our ten-year-old handbook. John and I went to work, and with the assistance of Evin Oneale of the Wyoming Cooperative Fish and Wildlife Research unit, and Bill Hepworth and John Schneidmiller of the WGFD, have just completed the second edition. This edition is over 600 pages and titled "The Handbook of Wildlife Depredation Techniques." Neither of us care to be around when a third edition is needed. In this handbook we have attempted to cover any type of damage situation our personnel may encounter. Although the primary function of this manual is to inform department personnel about proper and uniform damage prevention and evaluation techniques, it also provides relative and pertinent information concerning the many aspects of wildlife depredation. Information for this handbook has been compiled from techniques developed by our personnel, personnel from other states and provinces, and published data on wildlife depredation. There are nine chapters, a reprint, and Appendix section in this handbook. We will briefly summarize each chapter regarding its contents.