Python Unittest. Testing a method that prints dynamic data

I am very new to unittest in python (and testing generally). I have written a simple console application which offers the user multiple options which they can choose by entering a number (1-15), and I have a function that, once the input has been checked, prints a response to screen. In addition the response changing depending on the users choice, the response is also dependant on data held in text files and as such is subject to change.

How do I go about testing a function like this?

Thanks