Add a testing framework

This project doesn't have a testing framework and to make the app work more efficiently we will need a testing framework. Find testing frameworks for cpp and comment down below comparing all the available frameworks.

No files, tests, or entry points are mentioned. Start by reviewing the C++ project structure and identifying how the application is built, then research suitable C++ testing frameworks and compare their fit, setup, and capabilities. Done means posting a clear comparison that supports a framework choice.

Written by the indexing model from the issue text.