The testing of systems using tools such as JUnit is well known to the sequential programming community. It is perhaps less well known to the parallel computing community because it relies on systems terminating so that system outputs can be compared with expected outputs. A highly parallel architecture is described that allows the JUnit testing of non-terminating MIMD process based parallel systems. The architecture is then extended to permit the sampling of a continuously running system. It is shown that this can be achieved using a small number of additional components that can be easily modified to suit a particular sampling situation. The system architectures are presented using a Groovy implementation of the JCSP and JUnit packages.