Dual programming approach to software testing

The testing phase of the software development process consumes about one-half of the development time and resources. This paper addresses the automation of the analysis stage of testing. Dual programming is introduced as one approach to implement this automation. It uses a higher level language to duplicate the functionality of the software under test. We contend that a higher level language (HLL) uses fewer lines of code than a lower level language (LLL) to achieve the same functionality, so testing the HLL program will require less effort than testing the LLL equivalent. The HLL program becomes the oracle for the LLL version. This paper describes experiments carried out using different categories of applications, and it identifies those most likely to profit from this approach. A metric is used to quantify savings realized. The results of the research are: (a) that dual programming can be used to automate the analysis stage of software testing; (b) that substantial savings of the cost of this testing phase can be realized when the appropriate pairing of primal and dual languages is made, and (c) that it is now possible to build a totally automated testing system. Recommendations are made regarding the applicability of the method to specific classes of applications.