R – NHibernate Session and Repository

Not too sure about ActiveRecord, but in NHibernate a transaction belongs to a session, not the otherway round.

If you've used ADO.Net a lot, this will make more sense, as to create an IDbTransaction you need to use the connection. ActiveRecord's TransactionScope (and NHibnerate's ITransaction) essentially wrap an IDbTransaction, so you need to create the SessionScope before the TransactionScope.

What you might also find (depending on if you're using NHibernate 1.2 GA or NHibernate 2.*, and what FlushMode your SessionScope has) is that your call to FindAll() may cause the session to flush anyway, as NHibernate will realise that it can't retrieve the correct data without actioning the last call to Save.

This all said and done, have you tried using SessionScope.Flush() instead of creating a new SessionScope?

In our WCF Service we actually use a UnitOfWork which wraps a single operation and stores the ISession for that operation.

The repositories know how to get an ISession from the current unit of work they are running under.

In terms of testing we have a base test class that any test class which contains tests that touch the database inherits from. We then control the starting and ending of a unit of work in the testfixturesetup. Has worked fairly well for us once you get use to the fact that in the version of NUnit we use teardown is NOT guaranteed to run (in case of an unhandled exception during setup or the test).