Functional test automation is increasingly adopted by web applications developers. In particular, 2nd generation tools overcome the limitations of 1st generation tools, based on screen coordinates, by providing APIs for easy selection and interaction with Document Object Model (DOM) elements. On the other hand, a new, 3rd generation of web testing tools, based on visual image recognition, brings the promise of wider applicability and simplicity. In this paper, we consider the problem of the automated creation of 3rd generation visual web tests from 2nd generation test suites. This transformation affects mostly the way in which test cases locate web page elements to interact with or to assert the expected test case outcome.

Our tool PESTO determines automatically the screen position of a web element located in the DOM by a DOM-based test case. It then determines a rectangle image centred around the web element so as to ensure unique visual matching. Based on such automatically extracted images, the original, 2nd generation test suite is rewritten into a 3rd generation, visual test suite. Experimental results show that our approach is accurate, hence potentially saving substantial human effort in the creation of visual web tests from DOM-based ones.