An Experimental Study to Compare the Use of Metamorphic Testing and Assertion

(Department of Computer Science, The University of Hong Kong, Pokfulam, Hong Kong) (Department of Computer Science, City University of Hong Kong, Tat Chee Avenue, Hong Kong) (Department of Computer Science, The University of Hong Kong, Pokfulam, Hong Kong) (China Merchants Bank, Central, Hong Kong) + Corresponding author: Phone: +852 2788 9684, Fax: +852 2788 8614, E-mail: [email protected], http://www.cs.cityu.edu.hk/~wkchan/ Abstract: A test oracle in software testing is a mechanism for checking whether the program under test behaves correctly for any execution. In some practical situations, oracles can be unavailable or too expensive to apply. Metamorphic testing (MT) was proposed to alleviate this problem so that software can be delivered under the time-to-market pressure. However, the effectiveness of MT has not been studied adequately. This paper conducts a controlled experiment to investigate the cost effectiveness of using MT. The fault detection capability and time cost of MT are compared with the standard assertion checking method. Our results show that MT has potentials to detect more faults than the assertion checking method. The experiment results also show a trade-off between the two testing methods: MT can be less efficient but more effective, and can be defined at a coarser level of granularity than the assertion checking method.