* add tests which suppose to pass
* Update ConfigFileTest.cpp
* Update ConfigFileTest.cpp
* style: pre-commit.ci fixes
* add the possibility for an empty vector result if allowed.
* style: pre-commit.ci fixes
* add empty vector command line tests
* update book and readme
* add no default test
Co-authored-by: puchneiner <90352207+puchneiner@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>