Obviously, any real-world system will be more complicated than our example. There's a limit to what a code analysis can discover just by looking at it carefully, and plans often don't survive contact with the real world.
Any division needs to be validated to ensure that it will have the expected result and that the effort will be worth it. So double-check that the system is working the way you think it is working.
The ability to know how a live system is working is called observability. The main tools for it are metrics and logs. The problem you'll find is that they will normally be configured to reflect external requests and give no information about internal modules. We will talk about the observability of systems in depth in Chapter 10, Monitoring Logs and Metrics. You can refer to it for more information and apply the...
