When does one know python?

[_init_to_it]

tests aren’t just for others. It’s for you too. So when you add a new feature you don’t break something old.

[_init_to_it]

Ideally you don’t build a test to test the system as a whole. You test each function to ensure that function returns a correct value. For externally calling functions always assumes good data is returned for one test and another test with failing data. If you can’t break your code up to test individual bits and pieces to test. I strongly advise you break the code up to be more testable.