  The gradual deployment of intelligent and coordinated devices in the
electrical power system needs careful investigation of the interactions between
the various domains involved. Especially due to the coupling between ICT and
power systems a holistic approach for testing and validating is required.
Taking existing (quasi-) standardised smart grid system and test specification
methods as a starting point, we are developing a holistic testing and
validation approach that allows a very flexible way of assessing the system
level aspects by various types of experiments (including virtual, real, and
mixed lab settings). This paper describes the formal holistic test case
specification method and applies it to a particular co-simulation experimental
setup. The various building blocks of such a simulation (i.e., FMI, mosaik,
domain-specific simulation federates) are covered in more detail. The presented
method addresses most modeling and specification challenges in cyber-physical
energy systems and is extensible for future additions such as uncertainty
quantification.
