Setting up the test data and pretty printing the tree is part of the learning process. I'd say it is essential.
Writing pretty printers for trees is one of the best ways to verify you actually know how a tree works rather than having a superficial understanding of it.
> It's very odd that you have chosen to declare this "improper" and discredit it as a result of your own misunderstanding.
Because that's not the proper way to learn binary trees. I felt I gave good reasons for why. You learn binary trees by building one yourself. That's the best way.
So you use data provided by others. You use pretty printers provided by others. You use implementation provided by others. So what have you learned?
Part of the learning process, especially in algorithms, is creating your own data ( to test edge cases, speed, etc ). Part of learning is setting up your own pretty printer because it sure isn't trivial the first time you do it.
Something as fundamental like binary trees and algorithms should be taught/learned properly.