How to write Test Cases in Pen and Paper Interview?

I recently gave a Technical Pen and Paper interview in which the interviewer told me to write some test cases for a function whose working has not been told to me.

Input : Date of the form DD-MM-YYYY

Output : The date of next day as output in same format

The way I did it was to make two columns of Input and Expected output.

What is the correct/expected way of writing test cases for the following function ? And what are some important test cases one should cover for the same?