Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is an older version of Boost and was released in 2022. The current version is 1.91.0.

unit_test::runner::on_fail

Called for each failing condition.

virtual
void
on_fail(
    std::string const&);