Comment by worldsayshi

I suspect we're thinking about quite different use cases for our testing code. If the input-output pairs are describing a highly technical relationship I would probably want a more rigorous testing procedure. Possibly proofs.

Most of the tests I write daily is about moving and transforming data in ways that are individually rather trivial, but when features pile up, keeping track of all requirements is hard, so you want regression tests. But you also don't want a bunch of regression tests that are hard to change when you change requirements, which will happen. So you want a decent amount of simple tests for individually simple requirements that make up a complex whole.