The map wont do validation but the pipeline should. I recall that this would through a messaging error into the msgbox.
now when you test, it may not throw an error if you have output validation turned off… go to the .btm file in your solution and go to properties, (where you would specify the test instance file and type) and make sure that you have output validation turned on…. BUT it may still output a file with the faulty data but will have an error in our output box in VS.
go ahead and deploy your solution and give it a shot… i may be totally off.