That still won't help. For example how would you verify the "right" thing is done with the backlight in various power states? You'd need some ACPI independent way of finding out what is going on with the backlight, in which case why use ACPI. How would you work out if various things have been put into their most power efficient modes, versus just working correctly modes? Writing such a test suite that was comprehensive would be a humungous effort, and as Matthew points out would still miss all sorts of cases and ordering. For example the firmware may do the right thing if the graphics subsystem completes initialisation before the backlight, but get things wrong if the backlight is done first or concurrently.

There are ACPI test suites which verify the big picture, but it is the little details, hardware and ordering that really matters and is far harder to address. Example test suite https://wiki.linaro.org/LEG/Engineering/test-acpi