Fixes SaturnX (#69765)

code/modules/unit_tests/_unit_tests.dm

@@ -143,6 +143,7 @@
 #include "screenshot_antag_icons.dm"
 #include "screenshot_basic.dm"
 #include "screenshot_humanoids.dm"
+#include "screenshot_saturnx.dm"
 #include "security_officer_distribution.dm"
 #include "security_levels.dm"
 #include "serving_tray.dm"

code/modules/unit_tests/screenshot_saturnx.dm

@@ -0,0 +1,23 @@
+/// A screenshot test for making sure invisible limbs function, keeping them clothed so we know they're there.
+/datum/unit_test/screenshot_saturnx
+
+/datum/unit_test/screenshot_saturnx/Run()
+	var/mob/living/carbon/human/human = allocate(/mob/living/carbon/human/dummy/consistent) //we don't use a dummy as they have no organs
+	human.equipOutfit(/datum/outfit/job/assistant/consistent, visualsOnly = TRUE)
+
+	var/datum/reagent/drug/saturnx/saturnx_reagent = new()
+
+	saturnx_reagent.expose_atom(human, 15)
+	saturnx_reagent.turn_man_invisible(human, requires_liver = FALSE) //immediately turn us invisible
+
+	test_screenshot("invisibility", get_flat_icon_for_all_directions(human))
+
+/datum/unit_test/screenshot_saturnx/proc/get_flat_icon_for_all_directions(atom/thing)
+	var/icon/output = icon('icons/effects/effects.dmi', "nothing")
+	COMPILE_OVERLAYS(thing)
+
+	for (var/direction in GLOB.cardinals)
+		var/icon/partial = getFlatIcon(thing, defdir = direction)
+		output.Insert(partial, dir = direction)
+
+	return output