测试之重-人机交互与虚拟现实研究中心.pptVIP

山东大学计算机学院 Chapter 18 Product Quality outline Illustrate the relationship between the number of defects found during compiling and testing and the number that will be left in your finished products. Describe steps you can take to improve the quality of your programs. Quality comes first Two types of software engineers: Rush through the design and coding steps so as to start testing; Design and coding carefully and with careful review before compiling and testing How about you? Finding defects early Saving Time; Producing high quality product With the PSP,engineers focus on producing clean and defect-free program from the very beginning. Two metaphors Taking design and coding as producing the product, and testing as maintaining of the product Once you produce a sloppy product, no tools can clean it up. Another metaphor, taking defects removing in the test phase as fishing in a pool More fishes you catch, more fishes you leave in the pool. Difficulties of finding defects in testing Defects mask or aggravate other defects Interactions of defects complicate the defect identification and correction; One defects may mask the symptoms of other defects and this increases the chance that they will escape defection altogether. So large number of logic paths to test even for a modest-sized program 60 possible characters, a 10-character string have 6010 Embarrassed problem of finding defects in testing phase You don’t know how to test and where should be tested Ease of finding defects in design and code review You review a smaller modules of your own codes; You know the logic of your codes and you know what it should do; You understand the unusual cases and odd conditions; So you’re the only person who can ensure the products are essentially defect-free. If you do not produce a defect-free program, no one else can do it for you! The filter view of defects removal Think of defects removal as a filter Each phase only removes some percentage of the defects that were in the produc