And we write tests to exercise our own assumptions about how the system will be used. It's way too often I write some tests for my code, I quickly arrive at use

And we write tests to exercise our own assumptions about how the system will be used. It's way too often I write some tests for my code, I quickly arrive at use cases and failure cases that I hadn't anticipated while writing for the optimal use case. Reality, on the other hand, is usually suboptimal.