From my understanding when offloading with OpenMP currently in Flang+OpenMP (borrowed from Clang’s flow) there’s a device dependency on the host where the host generated IR file is passed to the device so that it can load it and do some processing of it (primarily to synchronize kernel environment and argument metadata, perhaps more in the case of Clang with a more comprehensive feature set) and this can affect the device IR’s output (one of the main cases I can think of off the top of my head is with declare target’s link clause).
This is perhaps one thing this type of test might be able to facilitate/help with, but perhaps it’s easier than I think it is to have and test this kind of dependency in the current MLIR test infrastructure.