Adding a method to return the entity manager.
Verifies that we can assert for exceptions.

This means of testing assertions allows for additional testing even after the assertion was successful. However, like setExpectedException(), it will terminate the test on failure.
Supporting string conversion of user entities.
Adding a security user provider for user entities.
Registering the user provider as a service.
Using unaliased name for Doctrine's entity manager service.
Registering the user provider with the Security component.