The correct wiring of your Spring IoC container contexts.
Data access using ADO.NET or an ORM tool. This would include such things such as the correctness of SQL statements / or NHibernate XML mapping files.
The Spring Framework provides first class support for integration testing in the form of the classes that are packaged in the Spring.Testing.NUnit.dll library
The superclasses in this package are ideal for integration testing. Unit testing should not normally involve the Spring container,
but should test classes in isolation.