If automatic python test discovery is enabled but no tests run then scons fails in a very mysterious way: an error is reported and a tests/.tests/(stuff).failed file is written but neither that file nor any message gives a hint as to what is wrong. This is especially confusing if scons runs unit tests, as the user sees tests being run and passing, yet the final result is a failure with no explanation.

Please add a useful error message when this occurs. It can even be speculation, if necessary, e.g. "if no tests failed then it is likely no unit tests were run (other than possibly flake8)"