Mocking vs. Test DB?

Question

Earlier I asked this question How to correctly unit test my DAL?, one thing left unanswered for me is if to really test my DAL is to have a Test DB, then what is the role of

Answer 1

Putting unit tests into transactions that roll back sounds hacky. Instead of that I have code that cleans the database of any crud (i.e. anything that isn't static/reference data) before the tests run (i.e. in the constructor of my test class). When your tests fail it helps to have the data still in the database to inspect what the cause of the failure is.