In my expiriance maybe some mocking tool will help you mock your business objects withouth need to implement any interface or do code your fake data classes.
For example you may use MOQ framework in .NET projects.

However, really cool article. Keep up the good work.

Yes, this would be correct. Your ObjectMother would have specific scenarios of handling different invalid data. Also, you can pass in data to your fake database. Typically your logic will be handled in the business layer for validation, but if something does not get validated properly, you could put some logic in your fake service layer that would replicate what would happen if you were to do this in a real database.

Great article. So if you have several cases of invalid data you wanted to test, would you create one method to return a prefilled invalid object per case?

Example:

ObjectMother.GetInvalidSSNData();
ObjectMother.GetInvalidMailingAddressData();
ObjectMother.GetInvalidOrderTotalData();

Also, what about sending invalid data into the fake database – do you test that?

Thanks,

–Bruce