code/modules/unit_tests/~nova/custom_sprites/editor.dm

/proc/custom_sprite_test_close_pixel	Whether two GetPixel() results are the same colour to within the rounding iconforge and BYOND's icon procs differ by.
/proc/custom_sprite_test_paintable_point	The first pixel this draft may paint in one view.
/proc/custom_sprite_reopen_test_drawing	A version 1 drawing with one pixel painted at `x`, `y` in its Front view.