Catch2

Catch2 is a testing tool for C++ programmers. It lets developers write automated tests that check whether their code actually works the way they intended — catching bugs before users ever see them.

The framework is distributed as a single header file, which in practical terms means you drop it into your project and you're ready to go. No complex setup, no separate installation process. This simplicity is a deliberate design choice aimed at reducing friction for developers who want to add tests to their workflow.

The approach supports a few different testing philosophies. Test-driven development (TDD) means writing the test before the actual code, then building the code until it passes. Behavior-driven development (BDD) focuses on describing how the software should behave from a user's perspective. The tool accommodates both styles, so teams can work however suits them best. It also works with Objective-C, and potentially plain C, though C++ is the primary target.

This is for C++ developers who want a straightforward way to verify their code. Concrete examples: a team building a game engine might use it to confirm that their physics calculations produce correct results, or a startup writing financial software could test that their transaction logic handles edge cases properly. Any C++ project where reliability matters is a candidate.

The README is fairly sparse on deeper details — it points to separate documentation for a tutorial, reference material, and the rationale behind creating yet another testing framework. There's a community around it with a Discord channel and forum for questions. It supports modern C++ standards (C++11 through C++17 and later), with an older branch available for legacy C++03 codebases.