Justifying Software Testing in the 21st Century

The role of testing as a software verification activity was directly challenged at a recent practitioners´ conference. The speaker´s points were that testing cannot usefully demonstrate software dependability, that it is over-costly, and that there is a case to be made for omitting it from the (high-integrity) software development process altogether. This paper attempts to contrast verification techniques including testing against a variety of criteria. The principal rival techniques considered include two relatively new ones: advanced defect detection and formal verification. In both cases there are grounds for saying that their use will lead to ´better´ source code, but there is still ultimately a reliance on the compiler as the means to turn source code into executable code. Since compilers are generally flawed themselves it is argued that testing is the only ´ultimate guarantee´ of correct execution. The option of bypassing verification altogether by means of code generation is also considered, but makes no difference to the overall argument