Improving the effectiveness of test suite reduction for user-session-based testing of web applications

Context: Test suite reduction is the problem of creating and executing a set of test cases that are smaller in size but equivalent in effectiveness to an original test suite. However, reduced suites can still be large and executing all the tests in a reduced test suite can be time consuming. Objective: We propose ordering the tests in a reduced suite to increase its rate of fault detection. The ordered reduced test suite can be executed in time constrained situations, where, even if test execution is stopped early, the best test cases from the reduced suite will already be executed. Method: In this paper, we present several approaches to order reduced test suites using experimentally verified prioritization criteria for the domain of web applications. We conduct an empirical study with three subject applications and user-session-based test cases to demonstrate how ordered reduced test suites often make a practical contribution. To enable comparison between test suites of different sizes, we develop Mod_APFD_C, a modification of the traditional prioritization effectiveness measure. Results: We find that by ordering the reduced suites, we create test suites that are more effective than unordered reduced suites. In each of our subject applications, there is at least one ordered reduced suite that outperforms the best unordered reduced suite and the best prioritized original suite. Conclusions: Our results show that when a tester does not have enough time to execute the entire reduced suite, executing an ordered reduced suite often improves the rate of fault detection. By coupling the underlying system's characteristics with observations from our study on the criteria that produce the best ordered reduced suites, a tester can order their reduced test suites to obtain increased testing effectiveness. (C) 2012 Elsevier B.V. All rights reserved.