Adds a dirty var viewer in TESTING mode (#41498)

code/modules/admin/verbs/mapping.dm

@@ -36,6 +36,9 @@ GLOBAL_LIST_INIT(admin_verbs_debug_mapping, list(
 	/client/proc/cmd_admin_grantfullaccess,
 	/client/proc/cmd_admin_areatest_all,
 	/client/proc/cmd_admin_areatest_station,
+	#ifdef TESTING
+	/client/proc/see_dirty_varedits,
+	#endif
 	/client/proc/cmd_admin_test_atmos_controllers,
 	/client/proc/cmd_admin_rejuvenate,
 	/datum/admins/proc/show_traitor_panel,
@@ -84,7 +87,22 @@ GLOBAL_LIST_INIT(admin_verbs_debug_mapping, list(
 	SSblackbox.record_feedback("tally", "admin_verb", 1, "Show Camera Range") //If you are copy-pasting this, ensure the 2nd parameter is unique to the new proc!
 	SSblackbox.record_feedback("tally", "admin_verb", 1, "Show Camera Range")
 
+#ifdef TESTING
+GLOBAL_LIST_EMPTY(dirty_vars)
 
+/client/proc/see_dirty_varedits()
+	set category = "Mapping"
+	set name = "Dirty Varedits"
+
+	var/list/dat = list()
+	dat += "<h3>Abandon all hope ye who enter here</h3><br><br>"
+	for(var/thing in GLOB.dirty_vars)
+		dat += "[thing]<br>"
+		CHECK_TICK
+	var/datum/browser/popup = new(usr, "dirty_vars", "Dirty Varedits", 900, 750)
+	popup.set_content(dat.Join())
+	popup.open()
+#endif
 
 /client/proc/sec_camera_report()
 	set category = "Mapping"

code/modules/mapping/preloader.dm

@@ -20,6 +20,10 @@ GLOBAL_DATUM_INIT(_preloader, /datum/map_preloader, new)
 		var/value = attributes[attribute]
 		if(islist(value))
 			value = deepCopyList(value)
+		#ifdef TESTING
+		if(what.vars[attribute] == value)
+			GLOB.dirty_vars += "<font color=green>[what.type]</font> at [AREACOORD(what)] - <b>VAR:</b> <font color=red>[attribute] = [isnull(value) ? "null" : (isnum(value) ? value : "\"[value]\"")]</font>"
+		#endif
 		what.vars[attribute] = value
 
 /area/template_noop