So you need to design you assessment process to reflect the real world scenarios the hire will encounter. It's surprising to me to hear so many developers push back on this notion that you can't design a predictive hiring process. If you were hiring a dentist, wouldn't a great way to assess them be having them fill a cavity? Or asking a chef to make you your restaurant's signature recipe? It seems very logical and the key here is that the work sample is reflective of what they'll encounter on the job.