Add dump_env (#558)

* Add dump_env

* Create new global for env dump

.luacheckrc

@@ -56,7 +56,7 @@ local STD_BASE_CONTROL = 'lua52c+factorio+factorio_control+factorio_defines+fact
 --[Assume Factorio Control stage as default]--
 -------------------------------------------------------------------------------
 std = STD_CONTROL
-globals = {'print', 'math', 'table', '_DEBUG', '_CHEATS', 'ServerCommands'} -- RedMew-specific globals
+globals = {'print', 'math', 'table', '_DEBUG', '_CHEATS', '_DUMP_ENV', 'ServerCommands'} -- RedMew-specific globals
 max_line_length = LINE_LENGTH
 
 not_globals = NOT_GLOBALS

config.lua

@@ -1,5 +1,6 @@
 _DEBUG = false
 _CHEATS = false
+_DUMP_ENV = false
 local market_item = 'coin'
 
 global.config = {

control.lua

@@ -93,3 +93,6 @@ end
 if config.camera.enabled then
     require 'features.gui.camera'
 end
+if _DUMP_ENV then
+    require 'utils.dump_env'
+end

utils/dump_env.lua

@@ -0,0 +1,27 @@
+-- A small debugging tool that writes the contents of _ENV to a file when the game loads.
+-- Useful for ensuring you get the same information when loading
+-- the reference and desync levels in desync reports.
+require 'utils.table'
+local Event = require 'utils.event'
+local filename = 'env_dump.lua'
+local inspect = table.inspect
+
+-- Removes metatables and the package table
+local filter = function(item, path)
+    if path[#path] ~= inspect.METATABLE and item ~= 'package' then
+        return item
+    end
+end
+
+local function player_joined(event)
+    local dump_string = inspect(_ENV, {process = filter})
+    if dump_string then
+        local s = string.format('tick on join: %s\n%s', event.tick, dump_string)
+        game.write_file(filename, s)
+        game.print('_ENV dumped into ' .. filename)
+    else
+        game.print('_ENV not dumped, dump_string was nil')
+    end
+end
+
+Event.add(defines.events.on_player_joined_game, player_joined)