文档对象模型和动态html外文翻译(编辑修改稿)

文档对象模型和动态html外文翻译(编辑修改稿)内容摘要：

A,you make sure that the parameter pass is now correct,but you add code that sets a pointer you may not go back and test A independently again,you may not find evidence of the new fault until much later in testing,when it is not clear that A is the culprit. In the same way,maintenance may introduce new enhancements require changes to the requirements,the system architecture,the program design,and the implementation itself,so many kinds if faults can be inserted as the enhancement is described,designed,and addition,the system may not function properly because users do not understand how the system was designed to the documentation is unclear or incorrect,a fault may factors,including user perception,play a large role in understanding the system an interpreting its messages and required who are not fortable with the system may not exercise system functions properly or to greatest advantage. Test procedures should be through enough to exercise system function to everyone’s satisfaction:user,customer, the tests are plete,faults may remain we have been,the sooner we detect a fault,the better。 faults detected early are easier and cheaper to ,plete and early testing can helo not only to detect faults quickly,but also to isolate the causes more early. shows the reasons for faults,not evidence of testing aims to uncover as many faults as possible,it is concerned with where they may how faults are created gives us clues about where to look when testing a system. System Testing Process There are several steps in testing a system: testing testing testing testing The steps are illustrated in Figure step has a different focus,and a step’s success depends on its goal or ,it is helpful to review the purpose of each step of system testing. Process Objective. Initially,we test the functions performed by the begin with a set of ponents that were tested individually and then function test checks that the integrated system performs its functions as specified in the example,a function test of a bank account package verifies that the package can correctly credit a deposit,enter a withdrawal,calculate interest,print the balance,and so on. Once the test team is convinced that the functions work as specified,the performance test pares the integrated ponents with the nonfunctional system security,accuracy,speed,and reliability,constrain the way in which the system functions are instance,a performance test of the bank account package evaluates the speed with which calculations are made,the precision fo the putation,the security precautions required,and the response time to user inquiry. At this point,the system operates the way the designers call this a verified system。 it is the designers’ interpretation of the requirements ,we pare the system with the customer’s expectations by reviewing the requirements definitio。