Add Cmake file & unittests

Would you please add the Cmake file you used to generate the Makefile? Also the blog post contains some unittests that are missing in this repo. Could you add those, too? Thank you.

Start by inspecting the repository's existing Makefile and locating the blog post referenced in the issue. Compare the blog's unit tests with the tests currently present, then add the requested CMake file and missing tests. Done means the project builds through CMake and the recovered unit tests run successfully.

Written by the indexing model from the issue text.