Software developed for aircraft needing TA certification pretty much has to be done using a process following RTCA/DO-178C. My question regards low-level (sometimes called "derived") requirements:
Low-level requirements either refine high-level requirements, or express design decisions. I've been told a low-level requirement should be traceable to some statement or small block of code, and at DAL C and above, each piece of code needs to be traceable to a low-level requirement.
Do DERs want to see a test corresponding to each low-level requirement, or is that only so for the high-level requirements? Would it be OK to do testing at a function level ("unit testing") as low-level requirement testing, and are the DERs happy with that?