How do you test the code using jest ?

Question

I want to understand how and what should i test in the following code ? Any help is much appreciated!

https://code.sololearn.com/WT8J1U1W39Sq/?ref=app

Answer 1

Martin Taylor ty, but i did went through some tutorials and have an idea of how it works . Just can't understand how to apply that to my code like what parts to test .