Effort is a powerful tool that enables a convenient way to create unit tests for Entity Framework based applications.
It is basicly an ADO.NET provider that executes all the data operations on a lightweight in-process main memory database instead of a traditional external database. It provides some intuitive helper methods too that make really easy to use this provider with existing ObjectContext or DbContext classes. A simple addition to existing code might be enough to create data driven unit tests that can be run without the presence of the external database.