A method includes a step of executing a software function using a set of test arguments and obtaining a result corresponding to each of the set of test arguments, each result indicating one of a set of robust and non-robust results, a subset of test arguments corresponding to robust results. The method further includes defining a set of arguments based on the results and the set of test arguments, the set of arguments including the subset of test arguments. Thereafter, arguments of subsequent calls to the software function may thereafter be examined to determine whether they fall within the set of arguments.