AFAIK, this is not necessary for multi-configuration generators. Here I used VS.
cmake --build . --config Debug ctest --output-on-failure -C Debug Yes, I did present those, in the second part of my post https://lists.boost.org/Archives/boost/2020/03/248533.php
You wrote "Interestingly, if I feed the ctest with the build configuration, [...]" Hence my answer for a "CMake template workflow", aka a workflow that works everywhere independent of the generator. So no surprises and you did seem surprised. The initially showed commands to not set the build type at all, which is usually wrong. That is another issue is solved by following this "template workflow". I'm not even sure what `cmake --build .` is supposed to do for multi-config generators. I'd expect it to error out. Hope that helps, Alex