database setup for Unit testing Linq to Sql, where database have relationships

Question

I google around unit testing LINQ to SQL and people are using MockDatabase class where we have list and add data to those Lists.

This will fit in the scenarios where we dont have relationships. I am behind using some data or mdf file in the unit test project which will have the same structure as like my actual database with all relationships and LINQ-to-SQL dml statements will be thoroughly tested.

Any idea what kind of mock database can i use???