In the previous recipe, we used an integer return code to signal success or failure in test.cpp. This is fine for simple tests, but typically, we would like to use a testing framework that offers an infrastructure to run more sophisticated tests with fixtures, comparisons with numerical tolerance, and better error reporting if a test fails. A modern and popular test library is Catch2 (https://github.com/catchorg/Catch2). One nice feature of this test framework is the fact that it can be included in your project as a single-header library, which makes compilation and updating the framework particularly easy. In this recipe, we will use CMake in combination with Catch2, to test the summation code introduced in the previous recipe.