[MIRROR] Frame stacking fix and unit test addition. (#2833)

* Frame stacking fix and unit test addition. (#56287)

* Reverts #56205

* Allow things without density to bypass checks

* The rest of the owl

* The rest of the owl

* Doc and tweak

* More feex

* RCD machine frame unit test

* I suck

* AAAAA

* Bad at unit tests

* Revert unit tests (for including in another PR)

* Fix windoor_assembly return logic

* Comment /mob/living/proc/PushAM logic

* Windoor assembley logic tweak

* Fix frame stacking

* Unit test

* Better wording from macros?

* Frame stacking fix and unit test addition.

Co-authored-by: Timberpoes <silent_insomnia_pp@hotmail.co.uk>

code/modules/mob/living/living.dm

@@ -221,13 +221,23 @@
 	if(!client && (mob_size < MOB_SIZE_SMALL))
 		return
 	now_pushing = TRUE
-	var/t = get_dir(src, AM)
+	var/dir_to_target = get_dir(src, AM)
+
+	// If there's no dir_to_target then the player is on the same turf as the atom they're trying to push.
+	// This can happen when a player is stood on the same turf as a directional window. All attempts to push
+	// the window will fail as get_dir will return 0 and the player will be unable to move the window when
+	// it should be pushable.
+	// In this scenario, we will use the facing direction of the /mob/living attempting to push the atom as
+	// a fallback.
+	if(!dir_to_target)
+		dir_to_target = dir
+
 	var/push_anchored = FALSE
 	if((AM.move_resist * MOVE_FORCE_CRUSH_RATIO) <= force)
-		if(move_crush(AM, move_force, t))
+		if(move_crush(AM, move_force, dir_to_target))
 			push_anchored = TRUE
 	if((AM.move_resist * MOVE_FORCE_FORCEPUSH_RATIO) <= force)			//trigger move_crush and/or force_push regardless of if we can push it normally
-		if(force_push(AM, move_force, t, push_anchored))
+		if(force_push(AM, move_force, dir_to_target, push_anchored))
 			push_anchored = TRUE
 	if((AM.anchored && !push_anchored) || (force < (AM.move_resist * MOVE_FORCE_PUSH_RATIO)))
 		now_pushing = FALSE
@@ -235,7 +245,7 @@
 	if (istype(AM, /obj/structure/window))
 		var/obj/structure/window/W = AM
 		if(W.fulltile)
-			for(var/obj/structure/window/win in get_step(W,t))
+			for(var/obj/structure/window/win in get_step(W, dir_to_target))
 				now_pushing = FALSE
 				return
 	if(pulling == AM)
@@ -243,8 +253,8 @@
 	var/current_dir
 	if(isliving(AM))
 		current_dir = AM.dir
-	if(AM.Move(get_step(AM.loc, t), t, glide_size))
-		Move(get_step(loc, t), t)
+	if(AM.Move(get_step(AM.loc, dir_to_target), dir_to_target, glide_size))
+		Move(get_step(loc, dir_to_target), dir_to_target)
 	if(current_dir)
 		AM.setDir(current_dir)
 	now_pushing = FALSE

code/modules/reagents/chemistry/machinery/reagentgrinder.dm

@@ -12,7 +12,6 @@
 	circuit = /obj/item/circuitboard/machine/reagentgrinder
 	pass_flags = PASSTABLE
 	resistance_flags = ACID_PROOF
-	anchorables = list(/obj/structure/table)
 	var/operating = FALSE
 	var/obj/item/reagent_containers/beaker = null
 	var/limit = 10

code/modules/unit_tests/_unit_tests.dm

@@ -60,6 +60,7 @@
 #include "pills.dm"
 #include "plantgrowth_tests.dm"
 #include "projectiles.dm"
+#include "rcd.dm"
 #include "reagent_id_typos.dm"
 #include "reagent_mod_expose.dm"
 #include "reagent_mod_procs.dm"

code/modules/unit_tests/rcd.dm

@@ -0,0 +1,46 @@
+/**
+ * Simple unit test to ensure there's no regression in behaviour where machine frames should not be stacked.
+ *
+ * We attempt to use the RCD to build multiple stacked machine frames on a turf. If we end up with any number that
+ * is not equal to 1, this means we've either built no machine frames (bad) or built more than one (regression).
+ *
+ * If this is successful, we attempt to spawn in some no-density machines that result in machine frames and we run
+ * the test again on our turf containing our single frame, deconstructing the machines! This should also not spawn
+ * any stacked machine frames.
+ */
+/datum/unit_test/frame_stacking/Run()
+	// First test - RCDs stacking frames.
+	var/obj/item/construction/rcd/rcd = allocate(/obj/item/construction/rcd/combat/admin)
+	var/mob/living/carbon/human/engineer = allocate(/mob/living/carbon/human)
+
+	engineer.put_in_hands(rcd, forced = TRUE)
+
+	rcd.mode = RCD_MACHINE
+
+	var/list/adjacent_turfs = get_adjacent_open_turfs(engineer)
+
+	if(!length(adjacent_turfs))
+		Fail("RCD Test failed - Lack of adjacent open turfs. This may be an issue with the unit test.")
+
+	var/turf/adjacent_turf = adjacent_turfs[1]
+
+	for(var/i in 1 to 10)
+		adjacent_turf.rcd_act(engineer, rcd, rcd.mode)
+
+	var/frame_count = 0
+	for(var/obj/structure/frame/machine_frame in adjacent_turf.contents)
+		frame_count++
+
+	TEST_ASSERT_EQUAL(frame_count, 1, "Expected RCD machine frame stacking test to end up with exactly 1 machine frame.")
+
+	// Second test - Deconstructing stacked machines to stack frames. We'll recycle our old turf to accomplish this.
+	for(var/i in 1 to 10)
+		// This should be a type path to a machine with no density, that can be wrenched on a turf with another machine of the same type.
+		var/obj/machinery/new_machine = new /obj/machinery/recharger(adjacent_turf)
+		new_machine.deconstruct(TRUE)
+
+	frame_count = 0
+	for(var/obj/structure/frame/machine_frame in adjacent_turf.contents)
+		frame_count++
+
+	TEST_ASSERT_EQUAL(frame_count, 1, "Expected no density machine deconstruction frame stacking test to end up with exactly 1 machine frame.")