doctest brings the ability of compiled languages such as D, Rust and Nim to write tests right next to the production code to C++.

doctest - "The Fastest C++ Testing Framework" - version 2.3 released

by Viktor Kirilov

From the article:

Version 2.3 brings an extensible reporter system and a few already implemented reporters with the framework - most importantly one for XML - vital for Continuous Integration (CI) workflows. Huge thanks to the Catch2 project for paving the way for single header testing libraries.