Test the boundary cases and invariants that would silently break if the rule were misunderstood.
Good tests preserve the real behavior the lesson is trying to make explicit. Connect the idea to a realistic coding decision so recall is easier when solving similar questions.
Additional Notes
What testing lens fits when to use a class?
Track: Python
Topic: Classes and Objects
Focus: When To Use A Class
Topics:Classes and ObjectsPythonWhen To Use A Class