Formalization of Mutation Operators

Software testing is a significant phase in any software development lifecycle irrespective of the type of software being developed. The main goal of software testing phase is to minimize the software faults in a system and increase its reliability. A software fault is an unintended mistake that causes failure of the system or any system component. Therefore, it is vital that the system is tested for most faults. One of the popular approaches to achieve a fault-free system is to induce, test and remove the faults from the system, commonly known as Mutation Testing. It uses mutation operators to induce and test faults in program. Furthermore, a software fault type (a textual description of a specific kind of fault that can occur in any program) encompasses one or more mutation operators. As the mutation operators induce a specific fault in the program, there is a need for a formal definition for each mutation operator representing a precise software fault that falls under an explicit software fault type. Literature research shows the lack of formalization of mutation operator definitions and as a consequence, it becomes difficult to induce a precise fault in a program. In this paper, the author illustrates a formal methodology to define mutation operator to induce a specific faults in programs written using object-oriented programming languages. The formalization of operators shows the need for new mutation operators that have not been defined for object-oriented programs.