[MIRROR] Properly unreg's turf changed when space openspace is deleted [MDB IGNORE] (#22294)

* Properly unreg's turf changed when space openspace is deleted

* merge conflict

---------

Co-authored-by: LemonInTheDark <58055496+LemonInTheDark@users.noreply.github.com>
Co-authored-by: Bloop <vinylspiders@gmail.com>

_maps/shuttles/emergency_tram.dmm

@@ -246,9 +246,6 @@
 	},
 /turf/open/floor/mineral/titanium/yellow,
 /area/shuttle/escape)
-"aU" = (
-/turf/open/openspace/airless,
-/area/template_noop)
 "aV" = (
 /obj/machinery/light/directional/east,
 /obj/item/radio/intercom/directional/north,
@@ -426,7 +423,7 @@ ak
 aQ
 ak
 aj
-aU
+aa
 aj
 ak
 aW
@@ -435,7 +432,7 @@ aW
 ak
 ak
 aj
-aU
+aa
 aj
 ak
 ak
@@ -460,7 +457,7 @@ aO
 aE
 aS
 ak
-aU
+aa
 ak
 aE
 aE
@@ -469,7 +466,7 @@ aE
 aE
 aP
 ak
-aU
+aa
 ak
 aX
 bc
@@ -664,7 +661,7 @@ aE
 aE
 aE
 ak
-aU
+aa
 ak
 aV
 aE
@@ -673,7 +670,7 @@ aE
 aE
 aE
 ak
-aU
+aa
 ak
 bb
 bd
@@ -698,7 +695,7 @@ ab
 ab
 ak
 aj
-aU
+aa
 aj
 ak
 ab
@@ -707,7 +704,7 @@ ab
 ab
 ak
 aj
-aU
+aa
 aj
 ak
 ak

code/game/turfs/open/openspace.dm

@@ -23,6 +23,8 @@
 // I am so sorry
 /turf/open/openspace/Initialize(mapload) // handle plane and layer here so that they don't cover other obs/turfs in Dream Maker
 	. = ..()
+	if(PERFORM_ALL_TESTS(focus_only/openspace_clear) && !GET_TURF_BELOW(src))
+		stack_trace("[src] was inited as openspace with nothing below it at ([x], [y], [z])")
 	RegisterSignal(src, COMSIG_ATOM_AFTER_SUCCESSFUL_INITIALIZED_ON, PROC_REF(on_atom_created))
 	var/area/our_area = loc
 	if(istype(our_area, /area/space))

code/game/turfs/open/space/space.dm

@@ -251,6 +251,8 @@
 
 /turf/open/space/openspace/Initialize(mapload) // handle plane and layer here so that they don't cover other obs/turfs in Dream Maker
 	. = ..()
+	if(PERFORM_ALL_TESTS(focus_only/openspace_clear) && !GET_TURF_BELOW(src))
+		stack_trace("[src] was inited as openspace with nothing below it at ([x], [y], [z])")
 	icon_state = "pure_white"
 	// We make the assumption that the space plane will never be blacklisted, as an optimization
 	if(SSmapping.max_plane_offset)
@@ -261,6 +263,13 @@
 	. = ..()
 	AddElement(/datum/element/turf_z_transparency)
 
+/turf/open/space/openspace/Destroy()
+	// Signals persist through destroy, GO HOME
+	var/turf/below = GET_TURF_BELOW(src)
+	if(below)
+		UnregisterSignal(below, COMSIG_TURF_CHANGE)
+	return ..()
+
 /turf/open/space/openspace/zAirIn()
 	return TRUE
 

code/modules/unit_tests/create_and_destroy.dm

@@ -119,6 +119,9 @@ GLOBAL_VAR_INIT(running_create_and_destroy, FALSE)
 	ignore += subtypesof(/obj/machinery/airlock_controller)
 	// Always ought to have an associated escape menu. Any references it could possibly hold would need one regardless.
 	ignore += subtypesof(/atom/movable/screen/escape_menu)
+	// Can't spawn openspace above nothing, it'll get pissy at me
+	ignore += typesof(/turf/open/space/openspace)
+	ignore += typesof(/turf/open/openspace)
 
 	var/list/cached_contents = spawn_at.contents.Copy()
 	var/original_turf_type = spawn_at.type

code/modules/unit_tests/focus_only_tests.dm

@@ -36,5 +36,8 @@
 /// Checks for bad icon / icon state setups in cooking crafting menu
 /datum/unit_test/focus_only/bad_cooking_crafting_icons
 
+/// Ensures openspace never spawns on the bottom of a z stack
+/datum/unit_test/focus_only/openspace_clear
+
 /// Checks to ensure that variables expected to exist in a job datum (for config reasons) actually exist
 /datum/unit_test/focus_only/missing_job_datum_variables