Create a Test file containing test to perform.

I want to be able to easily run tests to check the performance.

The best solution is to create a test namespace containing functions to make tests.
Potentially I will need to create config files to set the initial values.

In the meantime the tests are hardcoded in the `main.cpp`

Start with main.cpp, where the tests are currently hardcoded. Clarify the intended test namespace, test functions, and any configuration files needed for initial values before choosing an entry point. Done means performance checks can be run from the new test setup without relying on hardcoded tests in main.cpp.

Written by the indexing model from the issue text.