[skydhash]

Reaching the correct outcome is easy. That’s what happy path means. The time sink is all the error cases, ensuring that one of the transition in the system does not result in an unsatisfactory outcome.

That’s why we read code. Because only there the correct and incorrect cases are clearly separated.

[efficax]

But that's just more data. Create the error conditions in your test harness and exercise them. The machine will tell you what happened. Then correct the machine.

[krupan]

You make it sound so easy. Have you ever worked in QA?