需求和测试的关系

Requirements and Testing
As has been discussed above, testing is closely related to requirements at every level. In its broadest sense, testing is any activity that allows defects in the system to be detected or prevented, where a defect is a departure from requirements. So testing activities include reviews, inspections, analysis through modelling as well as the classical tests of components, subsystem and systems that are carried out. Because of the diversity of testing activities, the term qualification is used in this book to refer to all such activities.
The classic software testing mantra is “test early, test often.” In the same vein, qualification should begin as early as possible, since waiting until the system is almost complete before carrying out any kind of testing can lead to very expensive design changes and rebuilds. The earliest kinds of qualification action take place during the design of the system, and include requirements reviews, design inspections, and various forms of analysis carried out on system models. Likewise, qualification should occur often, in the sense that the same system function may be addressed in multiple stages, such as early analysis, design reviews, system tests and qualification tests.