C++ Automated Test Cases in Headers

 Catch2 is a multi-paradigm test framework for C++, which also
 supports Objective-C (and maybe C). It is primarily distributed as a
 single header file, although certain extensions may require
 additional headers.
 .
 If you've been using an earlier version of Catch, please see the
 Breaking Changes section of the release notes before moving to
 Catch2.