Microsoft has done work on automatic generation of unit tests, based on code contracts and parameterized unit test. E.g. the contract says the count must be increased by one when an item is added to a collection, and the parameterized unit test say how to add “n” items to a collection. Pex will then try to create a unit test that proves the contract is broken. See this video for a overview.
If this works, your unit test will only have to be written for one example of each thing you are trying to test, and PEX will be able to then work out witch data items will break the test.
