Testing reactivity

The testServer() function (since Shiny 1.5.0) makes it possible to test code in server functions and modules, without needing to run the full Shiny application with the following characteristics:

• The UI can not be used.
• You’ll need to add a browser() inside of testServer() to debug any problem.

Note: For this section, I took some examples the articule Server function testing from the original shiny documentation to have a complete view of how to use this functionality.