This one cropped up at work recently. As part of a project there was a requirement for an API to carry out a check as part of an update on an object to ensure that none of the object’s children met a certain criteria (I’m avoiding business context here).
I was working with a customer’s code base recently and I noticed a separate Unit test project was referencing an internal class in a different assembly. Initially, I expected a code smell and perhaps some kind of wrapper that was exposing an internal class some how. After doing a bit of digging and examining dependencies further with Resharper I drew a blank. How was this possible?