Parallel firm mutation of Java programs

Firm mutation was introduced as an intermediate form of mutation testing representing the middle ground between weak and strong mutation. In firm mutation, components may be groups of statements and partial program executions may be considered rather than each separate component execution as in strong mutation. Despite its flexibility and its potential for combining the reduced expense of weak mutation with the greater transparency of strong mutation, firm mutation has remained largely unexplored. One of the difficulties with firm mutation is that there has been no obvious systematic basic on which to select the areas of program code as candidates for firm mutation testing. The advent of object-oriented languages has, in a sense, provided a natural solution to this problem. The individual methods that form part of object classes tend to be small but cohesive components that lend themselves ideally to firm mutation. This paper considers such application of firm mutation to Java methods by exploiting the use of Java threads to perform mutant execution. The potential parallelism that this afros is another factor in the cost reduction envisaged.