Defect detection metrics

3 Defect detection metrics

Average defects per page = C/A = ––– 15 31 = 0.48

Average defects per page (standardized) = D/A = ––– 53 31 = 1.71

(3) Defects detection efficiency (hours per defect) = B/C = 20.5 –––– 15 = 1.37 (4)

Standardized defect detection efficiency (hours per standardized defect) = B/D = 20.5 –––– 53 = 0.39

Prepared by: ________________ Signature: __________________ Date: ___________ Anita McMahon Anita McMahon 8/5 Prepared by: ________________ Signature: __________________ Date: ___________ Anita McMahon Anita McMahon 8/5

Software testing – strategies

Chapter outline

9.1 Definition and objectives 180

9.2 Software testing strategies 182

9.3 Software test classifications 187

9.3.1 Classification according to testing concept 187

9.3.2 Classification according to requirements 188

9.4 White box testing 189

9.4.1 Data processing and calculation correctness tests

9.4.2 Correctness tests and path coverage 190

9.4.3 Correctness tests and line coverage 191

9.4.4 McCabe’s cyclomatic complexity metrics 194

9.4.5 Software qualification and reusability testing 196

9.4.6 Advantages and disadvantages of white box testing

9.5 Black box testing 197

9.5.1 Equivalence classes for output correctness tests

9.5.2 Other operation factor testing classes 201

9.5.3 Revision factor testing classes 205

9.5.4 Transition factor testing classes 207

208 Summary

9.5.5 Advantages and disadvantages of black box testing

209 Selected bibliography

211 Review questions

212 Topics for discussion

Software testing (or “testing”) was the first software quality assurance tool applied to control the software product’s quality before its shipment or installation at the customer’s premises. At first, testing was confined to the final stage of development, after the entire package had been completed. Later, as the importance of early detection of software defects penetrated quality assurance concepts, SQA professionals were encouraged to extend testing to the partial in-process products of coding, which led to software module (unit) testing and integration testing.

Common to all testing activities is their application through the direct 179 running of code, free of review of development documents. Some authors

Softw

tend to broaden the scope of testing even further and consider all software

life cycle quality assurance activities as types of testing activities. In this book, we limit the scope of testing to quality assurance activities performed

are tes

by running code. Software testing is undoubtedly the largest consumer of software quality assurance resources. In a survey performed in November 1994, Perry (1995)

ting – str

found that on average, 24% of the project development budget was allocat-

ed to testing. In addition, 32% of the project management budget was slated for testing activities. With respect to time resources, an average of 27% of project time was schedule for testing. The survey’s participants also indicated

a tegies

that they planned to allocate substantially more time (45% on average) to testing but that the pressures typically arising toward the close of projects gen- erally forced project managers to reduce the testing time scheduled.

Testing is certainly not the only type of SQA tool applied to software code. Additional tools are code inspections and code walkthroughs, methods implemented on code printout without actually running the program. These procedures, which are similar to those applied in design inspection and walk- throughs, yield good results in identifying code defects. Nevertheless, these tools, because they are based solely on the review of documents, can never replace testing, which examines the software product’s functionality in the form actually used by the customer. For further discussion of these software quality tools see Chapter 8.

This chapter is dedicated to testing strategies and test classifications. After defining testing and its objectives, the chapter discusses testing strate- gies and classifies them according to requirement types.

Additional material on testing can be found in the numerous papers and books dealing with software testing. A sample of these sources are the books by Beizer (1984), Perry (1995), Kit (1995), Jorgensen (1995), Kaner et al. (1999), Rubin (1994) and Perry and Rice (1997). Another valuable source of material on software testing can be found in the software engineering and software quality assurance literature, such as Pressman (2000), Sommerville (2001) and Hamlet and Maybee (2001), to mention but a few.

After completing this chapter, you will be able to:

Explain testing objectives.

Discuss the differences between the various testing strategies, their advan- tages and disadvantages.

Describe the concepts of black box testing and white box testing as well as discuss their advantages and disadvantages.

Define path coverage versus line coverage.

Describe the various types of black box tests.

9.1 Definition and objectives