code/modules/unit_tests/spritesheets.dm

/datum/unit_test/spritesheets	Checks if spritesheet assets contain icon states with invalid names
/datum/asset/spritesheet_batched/concurrent_test	A real sheet with a deterministic yield so queued loading and foreground consumers overlap.
/datum/unit_test/spritesheet_concurrent_loading	A queued load and a foreground caller of one batched sheet share one generation, cached or not, and a failed generation lets the next caller retry.