How to unit test my models now that I am using Core Data?

I have been developing an iphone application using a domain model, and have put off the persistence aspect of the app until now. Core Data looks like a really good solution since I already have a well defined model but I am running into a snag with my existing unit tests.

Here is simple example of what I have now:

- (void)test_full_name_returns_correct_string {
    Patient *patient = [[Patient alloc] init];  
    patient.firstName = @"charlie";
    patient.lastName = @"chaplin";
    STAssertTrue([[patient fullName] isEqualToString:@"charlie chaplin"], @"should have matched full name");
}  

How can I make this work once my Patient object extends from NSManagedObject and uses @dynamic for the firstName and lastName properties?

Has anyone else run into this type of this with Core Data? Thanks.