Turn derivation unit tests into unit characterization tests
(cherry picked from commit a6e587923c9d5d716fe0f0049bed96d1cc210bff)
Change-Id: Ia2a2e65aabfee8d5d52142b8fdaacbae4a27242c
Factor out bits of the worker protocol to use elsewhere
(cherry picked from commit 4b1a97338f517f45e6169d3d8845c5caa5724e97)
Change-Id: If93afa0f8b1cf9b0e705b34fa71e6fd708752758