Disclosed is a software testing system operative to test a software application, for example during runtime. There may be provided an apparatus for at least partially isolating, from within the software application, at least one highly coupled software component which performs a given function. Isolation may be performed by introducing, prior to execution, code elements for runtime access of application points associated with the at least one highly coupled software component. There may also be provided apparatus for removing or replacing a behavior of at least said at least partially isolated highly coupled software component during runtime.