Write a docs section on setting up a testing framework for MagicBox repos

[thoat]

Summary

Research on testing framework options for MagicBox repos and finish writing the Set up a testing framework section in the GitHub Workflow docs.

Details

PR #39 has completed the sections on continuous integration and code health checks. However, a need emerged as I wrote about setting up CodeClimate. That is, CodeClimate can read and display results from test coverage reports, but it does not run these reports by itself. Therefore, a test coverage tool needs to be set up. As I came to learn this, I also found out that MagicBox repos do not have a uniform test pattern / testing framework yet. This should be addressed among our dev's.