The example use case here would be a class library that sets up things for multiple test projects in a consistent way so that those test projects can reference this one library and run consistently across the board. MSTest, NUnit, and xUnit all support this scenario so, hopefully, this is indeed a bug, and not the intended behaviour.

Repro Steps:

1. create 2 projects; project A contains some tests, while project B contains a class with some hooks (e.g. before/after test)
2. make sure project A references project B, and make the class containing the tests inherit from the class in project B
3. put some breakpoints on the hooks and observe that they never get hit