Hi @cysiddiqui
The error clearly indicates because you are using value of -1, your test is failing as the error mentions it is looking for valid range of [0, 17]
I am also suspecting there is an issue with your assignment copy as the expected output shown in your pic is incorrect for exercise 4 unit test. I am sharing my assignment screenshot for the same exercise
Kindly get a fresh copy of the assignment and re-do the assignment. I am sharing a link on how to get a fresh copy.
Regards
DP