testscenarios copies the tests, it doesn't call the constructor for the class; this makes things a lot simpler than trying to reconstruct whatever state the object may have from scratch again.

As for str(test) and test.id() being different - well sure they are today, but I don't know that the str(test) format is /useful/ today, as its not a particularly good str() anyhow. It doesn't identify that its a test instance even. 

This suggests two alternatives to me:
 - decide that we want three things: id, friendly-id and shortDescription, and have three non-magic methods, which TextTestRunner can call depending on what the user wants to see.
 - decide we want two things, id and shortDescription, and TextTestRunner can combine these things to meet the users request. (e.g. id + ' ' + shortDescription)

And separately, as the __str__ isn't particularly good anyhow, perhaps we should take the opportunity to think about what we want from it and adjust it.