Code approver and test approver
2 answers
The precondition "Require Disinterested Approvers," which is available for the "Save Work Item" operation, may be of interest. Its description states, "Reviewers may not have created any of the change sets affiliated with the work item under review." If you also use a precondition that requires that an approval exists (either when delivering change sets to a stream or when transitioning a work item to a particular state), this should guarantee that someone other than the coder has approved of the change.
I don't know if this is quite what you want (because your question is very short on context and details), but it is the best tool I can find.
-- David Olsen, IBM Rational, Jazz Process Team