C++TESK Testing ToolKit is an open-source C++ based toolkit intended for automated functional testing of software components (mostly in C/C++) and RTL (HDL) models of digital hardware (in Verilog and VHDL). The main part of the toolkit is a library of C++ classes and macros that define facilities for constructing formal specifications (reference models), adapters of components under test, test scenarios and test coverage metrics. Basing on C++ descriptions provided by a user, a test system is compiled. It allows automatically generating and applying sequences of stimuli to the component under test, checking correctness of its reactions and collecting statistics on test execution. Besides the basic library, the toolkit includes a report generator, means for parallelizing test execution on computer clusters, and Eclipse-based IDE.