In some of my projects, I take a less purist approach to unit testing in that I allow unit tests to touch the database. In order to “reset” the database to the state it was in prior to the test, the code enlists COM+ 1.5 transactions via the [RollBack] attribute in MbUnit (there’s also one for NUnit).
My preference is to have a local copy of the database when developing, but there have been times when this was not possible and I needed to run my unit tests against a remote database I did not have full control over. The problem is that the RollBack enlists the local Distributed Transaction Coordinator to acquire a transaction. If the database server is on a remote server, it attempts to use Transaction Internet Protocol (TIP) instead which is disabled by default.
At the time, I was being lazy and left it alone, moving on to something else. Fortunately, my laziness has paid off as another smart person dug into it and figured out the details to getting this to work properly. See, sometimes laziness does pay off. ;) Thanks Steve!