Adds an implanting unit test (#13691)

* Adds an implanting unit test

* Update implanting.dm

* Update implanter.dm

code/game/objects/items/implants/implanter.dm

@@ -48,7 +48,7 @@
 		log_game(user, target, "implanted", src)
 		imp = null
 		update_icon()
-		return
+		return TRUE
 	to_chat(user, span_notice(" You fail to implant [target]."))
 
 /obj/item/implanter/neurostim

code/modules/unit_tests/_unit_tests.dm

@@ -50,6 +50,7 @@
 #include "component_tests.dm"
 #include "connect_loc.dm"
 #include "dcs_get_id_from_elements.dm"
+#include "implanting.dm"
 #include "initialize_sanity.dm"
 #include "keybinding_init.dm"
 #include "map_templates.dm"

code/modules/unit_tests/implanting.dm

@@ -0,0 +1,16 @@
+///Implants a human to make sure it effectively is inserted and deleted.
+/datum/unit_test/implanting
+
+/datum/unit_test/implanting/Run()
+	var/mob/living/carbon/human/implanted_guy = allocate(/mob/living/carbon/human)
+	var/obj/item/implanter/implanter_to_inject = allocate(/obj/item/implanter/cloak)
+
+	var/obj/item/implant/implant_in_planter = implanter_to_inject.imp
+
+	implanted_guy.put_in_active_hand(implanter_to_inject)
+
+	TEST_ASSERT(implanter_to_inject.attack(implanted_guy, implanted_guy), "[implanted_guy] failed to inject himself with [implanter_to_inject]")
+	TEST_ASSERT(!implanter_to_inject.imp, "[implanter_to_inject] still has an implant in its implanter, despite being injected into [implanted_guy]")
+
+	qdel(implanted_guy)
+	TEST_ASSERT(QDELETED(implant_in_planter), "[implant_in_planter] has been injected into [implanted_guy], who has been deleted, but the implant still exists.")