Simple.Data Aggregate Functions and InMemoryAdaptor

Could not find anything regarding this while searching Google or this site. We are currently unit testing Simple.Data queries using the InMemoryAdaptor to mock up the database. We've stumbled across some errors occurring when using the sum aggregate that works fine outside of the unit tests, but does not work while unit testing with the InMemoryAdaptor. I've searched for anything that has to be configured for the InMemoryAdaptor and came up empty. Can aggregate functions in Simple.Data be unit tested with the InMemoryAdaptor?

While I'm here, can table joins be tested as well? Our joins are working fine outside of the unit testing environment, and I know that the ConfigureJoin allows the InMemoryAdaptor to be set up for a join, but I've not yet been able to get that to work either.