Tea requires boiling water (100C) to brew properly. Giving me a pot of hot water and a tea bag will not allow me to make tea.
I currently work with a project that is controlled by a configuration file.
It has become useful recently to write unit tests for the config file.
We check simple things such as duplicate and even validate keys against a public api.
Given that we are integrating with over 100 services a mistake can cause a large amount of errors. Unit tests help here.