Help Needed: Code Review.

The first image is that of the code and the other two are that of the unit test. I am new to testing and would appreciate feedback on my initial attempts. Please review my test units to identify any mistakes or areas for improvement. I lack confidence in knowing whether I'm following the correct practices, as I'm relying on guidance from GPT and online sources. Constructive criticism is encouraged, and I'm open to guidance on testing. If you have any recommended resources that could assist me in improving my testing skills, please share them.