Chapter10-11.ppt

1、Advanced Software Engineering,Spring, 2010,R. S. Pressman, Software Engineering:A Practitioners Approach. McGraw-Hill,Professor Liu Qing,School of Software, Yunnan University,For the Postgraduates in School of Software,2020/8/25,2,Chapter 10Software Quality Assurance（P712),2020/8/25,3,OVERVIEW,This

2、chapter provides an introduction to software quality assurance (SQA). It is important to have the students understand that software quality work begins before the testing phase and continues after the software is delivered. The role of metrics in software management is reinforced in this chapter.,20

3、20/8/25,4,OVERVIEW,SQA is the concern of every software engineer to reduce cost and improve product time-to-market. A Software Quality Assurance Plan is not merely another name for a test plan, though test plans are included in an SQA plan. SQA activities are performed on every software project. Use

4、 of metrics is an important part of developing a strategy to improve the quality of both software processes and work products.,2020/8/25,5,10.1 Quality Concepts(p713),An important concept in this section is that controlling variation among products is what quality assurance work is all about. Softwa

5、re engineers are concerned with controlling the variation in their processes, resource expenditures (spends), and the quality attributes of the end products. The definitions of many quality concepts appear in this section. Students need to be familiar with these definitions, since their use in softw

6、are quality work does not always match their use in casual conversation.,2020/8/25,6,Why SQA Activities Pay Off?,cost to find,and fix a defect,100,10,log,scale,1,Req.,Design,code,test,system,test,field,use,1,3-6,10,15-40,30-70,40-1000,2020/8/25,7,Quality Concepts,general objective: reduce the “varia

7、tion between samples” . but how does this apply to software? quality control: a series of inspections, reviews, tests quality assurance: analysis, auditing(审计) and reporting activities cost of quality Appraisal (judgment) costs failure costs external failure costs,2020/8/25,8,Cost of Quality Prevent

8、ion costs - quality planning, formal technical reviews, test equipment, training Appraisal costs - in-process and inter-process inspection, equipment calibration (校准) and maintenance, testing Failure costs - rework, repair, failure mode analysis External failure costs - complaint resolution, product

9、 return and replacement, help line support, warranty (保修)work,2020/8/25,9,10.2 Software Quality Assurance(p716),This section describes software quality as conformance (符合/遵守) to explicitly (clearly) stated requirements and standards, as well as implicit characteristics that customers assume will be

10、present in any professionally developed software. The SQA group must look at software from the customers perspective (view), as well as assessing its technical merits (value). The activities performed by the SQA group involve quality planning, record keeping, analysis and reporting. SQA plans are di

11、scussed in more detail later in this chapter.,2020/8/25,10,Software Quality Assurance,2020/8/25,11,Software Quality Assurance Conformance (Obey) to software requirements is the foundation from which software quality is measured. Specified standards are used to define the development criteria that ar

12、e used to guide the manner in which software is engineered. Software must conform (follow) to implicit (not clear) requirements (ease of use, maintainability, reliability, etc.) as well as its explicit requirements.,2020/8/25,12,SQA Group Activities Prepare SQA plan for the project. Participate in t

13、he development of the projects software process description. Review software engineering activities to verify compliance (obedience) with the defined software process. Audit (审核) designated (appointed) software work products to verify compliance(符合) with those defined as part of the software process

14、. Ensure that any deviations (differences) in software or work products are documented and handled according to a documented procedure. Record any evidence of noncompliance and reports them to management.,2020/8/25,13,10.3 Software Reviews (p719),This section describes the purposes of conducting sof

15、tware reviews. It is important to point out to students that any work product (including documents) should be reviewed. Students are usually impressed by the fact that conducting timely reviews of all work products can often eliminate (erase) 80% of the defects before any testing is conducted. This

16、message often needs to be carried to managers in the field, whose impatience (want) to generate code sometimes makes them reluctant (unwilling) to spend time on reviews.,2020/8/25,14,Reviews & Inspections,. there is no particular reason,why your friend and colleague,cannot also be your sternest crit

17、ic.,Jerry Weinberg,2020/8/25,15,What Are Reviews?,a meeting conducted by technical people for technical people a technical assessment of a work product created during the software engineering process a software quality assurance mechanism a training ground,2020/8/25,16,What Reviews Are Not!,They are

18、 not:,a project budget summary,a scheduling assessment,an overall progress report,a mechanism for reprisal (报复） or political intrigue （阴谋）!,2020/8/25,17,The Players,2020/8/25,18,Conducting the Review,be preparedevaluate,product before the review,review the product, not,the producer,keep your tone mild, ask,questions instead of,making accusations (谴责),stick to the review agenda （议程）,raise issues, dont resolve them,avoid discussions of stylestick to technical,correctness,schedule reviews as project tasks,record and report all review results,1.,2.,3.,4.,5.,6.,7.,8.,2020/8/25,19,Review