[karmajunkie]

The definition of a refactoring (at least the one I give juniors) is the modification of a system of code such that an external contract remains valid. An external contract is typically validated by tests (though it doesn't have to be). If your refactoring crosses a unit boundary, you're certainly going to have to test at a higher level (assuming you want the safety of a contract validation through tests). Otherwise you're modifying the contract of the system under test and you've crossed over from refactoring to redesign and reimplementation.