A dependable cyber-physical system (CPS) correctly performs the functions for which it was conceived in its intended environment, without adverse effects. In particular, a dependable CPS responds correctly and timely even in situations where system parts have failed, either temporarily or permanently. This requirement also applies when tests check reliability, availability, and performance properties of these systems in the lab and in the field. A CPS with test probes built into all hardware and software components throughout its lifecycle can fulfill these requirements. Tests of such systems require that their architecture be designed for testability. Starting from here, we first characterize the CPS we use as an example: an integration platform of an X-by-wire eCar. We elaborate a series of design tactics that enable or improve the system's testability, focusing on test probes. Test probes can execute deterministic, efficient, and reliable real-time tests or act as safety monitors that observe and potentially intervene in a system. In this session, you will learn how to design a testable system that incorporates test probes as central system elements and how to write non-intrusive tests that yield reliable results.