How to generate junit tests given an XSD

Currently our XSD schema changes quite a bit and we want to it to create junit tests that will break whenever an existing data type gets re-defined.

For example, if there was a field "YearBuilt" defined as a "Integer" originally and someone comes along and changes this to be a "String", we want this jUnit test to fail.

Is there any utilities or programs which will take in an existing schema and generate the appropriate unit tests for all the datatypes? We currently generate jaxb objects. Is there some program which can generate junits for a set of jaxb objects?