While the NUT documentation implies that we support "device data dumps" and "scheduled event sequences" (with TIMER NNN lines) which are "generally named" with .dev and .seq extension respectively, current dummy-ups.c does not differentiate them and loops re-reading the file to apply its lines every second (so e.g. overwriting whatever SET VAR we test) as part of the same MODE_DUMMY handling.

For automated tests, it would be beneficial to define an e.g. MODE_DUMMY_ONCE (settable with driver parameters and defaulted according to file extension) to read the device info once and never loop back, so test data writes into the device remain in place as long as the driver process runs.