Pass data through to ItemEffects.partyAction for Gen 2 pack items

Both call sites -- Game2:usePartyItem (the field pack) and
BattleState:useItem (the battle pack) -- asked ItemEffects.partyAction
for an item's family with no `data` argument, even though every other
call in the same functions (useOnMon, usePpItem, applyPartyItem) passed
it through correctly. partyAction resolves through recordFor, which
reads data.gen2ItemEffects when given a dataset and falls back to the
module's own built-in RECORDS table when not -- so with no data, a
mod's own item_effects record was invisible and every mod-defined Gen 2
field or battle item resolved to a nil action, falling straight through
to "isn't going to help here" / "isn't going to help here" without ever
opening the party picker.

Both now pass the live dataset (self.data on Game2, self.game.data on
the battle screen) the same way their sibling calls already did.

src/core/Game2.lua

@@ -683,7 +683,10 @@ end
 -- .SelectMon / PPRestoreItem_Cancel carry path: nothing spent.
 function Game2:usePartyItem(itemId)
   local ItemEffects = require("src.core.gen2.ItemEffects")
-  local action = ItemEffects.partyAction(itemId)
+  -- without the merged dataset this can only ever see RECORDS, the
+  -- module's own built-ins, so a mod's field item resolves to no action
+  -- at all and never gets past the .Oak refusal below
+  local action = ItemEffects.partyAction(itemId, self.data)
   if not action then return end
   local party = (self.save and self.save.party) or {}
   if #party == 0 then

src/ui/gen2/BattleState.lua

@@ -3024,8 +3024,10 @@ function BattleState:useItem(itemId)
     -- Everything else the pack can spend on a party mon runs the same
     -- item_effects.asm routine the field pack runs: the potion line and the
     -- drinks, the status cures and their berries, REVIVE / MAX REVIVE, and
-    -- the ETHER / ELIXER family.
-    local action = ItemEffects.partyAction(itemId)
+    -- the ETHER / ELIXER family.  Without the merged dataset this can only
+    -- ever see RECORDS, the module's own built-ins, the same gap
+    -- Game2:usePartyItem had for the field pack.
+    local action = ItemEffects.partyAction(itemId, self.game and self.game.data)
     if action then
       return self:useOnPartyMon(itemId, action)
     end

tests/gen2_battle_items_test.lua

@@ -117,6 +117,27 @@ local DATA = {
       fieldMenu = "ITEMMENU_PARTY", battleMenu = "ITEMMENU_NOUSE" },
     OLD_ROD = { id = "OLD_ROD", pocket = "KEY", name = "OLD ROD",
       fieldMenu = "ITEMMENU_CURRENT", battleMenu = "ITEMMENU_NOUSE" },
+    -- a mod's own battle-pack item: its action lives only in
+    -- gen2ItemEffects below, which ItemEffects.RECORDS (the module's
+    -- built-in table) has never heard of (#8)
+    MOD_ITEM = item("MOD_ITEM"),
+  },
+  gen2ItemEffects = {
+    -- a status cure rather than an HP heal: HP is exposed to the wild
+    -- mon's own reply once the item spends the turn, which would make a
+    -- direct before/after HP check depend on incidental battle math this
+    -- fix has nothing to do with.  Status is not.
+    MOD_ITEM = {
+      action = "status", field = true, needsTarget = true,
+      use = function(ctx)
+        local mon = ctx.mon
+        if mon.status ~= "poison" then
+          return { used = false, text = "It won't have\nany effect." }
+        end
+        mon.status = nil
+        return { used = true, text = "MOD ITEM used!" }
+      end,
+    },
   },
 }
 
@@ -236,6 +257,33 @@ do
   eq(save.inventory.ANTIDOTE, 1, "with the ANTIDOTE untouched")
 end
 
+-- ---- a mod's own battle-pack item (#8) -------------------------------------
+-- BattleState:useItem asked ItemEffects.partyAction for the item's family
+-- with no `data` argument, the same omission Game2:usePartyItem had for the
+-- field pack, so a mod item's action -- present only in the merged
+-- gen2ItemEffects table -- resolved to nil and the pack fell straight to
+-- "That isn't going to help here." instead of opening the party list.
+do
+  local sick = Mon.new(DATA, "CYNDAQUIL", 10, { dvs = perfect })
+  sick.moves = { { id = "TACKLE", pp = 35, maxPp = 35 } }
+  sick.status = "poison"
+  local screen, _, _, save, pushed = newScreen({
+    player = sick, party = { sick }, inventory = { MOD_ITEM = 1 },
+  })
+  check(runToMenu(screen), "reached the menu")
+
+  screen:useItem("MOD_ITEM")
+  eq(screen.phase, "submenu",
+    "a mod's own gen2ItemEffects record opens UseItem_SelectMon")
+  local picker = pushed[#pushed]
+  eq(getmetatable(picker), PartyMenu, "and the pick is the party screen")
+  if picker and picker.onChoose then
+    picker.onChoose(1, sick)
+    eq(sick.status, nil, "the mod item's own use() ran through the real screens")
+    eq(save.inventory.MOD_ITEM, nil, "and the mod item was spent")
+  end
+end
+
 -- ---- IsItemUsedOnConfusedMon: the battle-only arm --------------------------
 do
   local screen, battle, player, save, pushed = newScreen({

tests/gen2_field_items_test.lua

@@ -102,6 +102,24 @@ local DATA = {
     TM01 = { id = "TM01", name = "TM01", pocket = "TM_HM", index = 191,
       fieldMenu = "ITEMMENU_PARTY", battleMenu = "ITEMMENU_NOUSE",
       teaches = "SWIFT" },
+    -- a mod's own field item, whose action lives only in gen2ItemEffects
+    -- below -- ItemEffects.RECORDS (the module's built-in table) has never
+    -- heard of it, so resolving it at all requires the merged dataset (#8)
+    MOD_ITEM = { id = "MOD_ITEM", name = "MOD ITEM", pocket = "ITEM",
+      index = 250, fieldMenu = "ITEMMENU_PARTY", battleMenu = "ITEMMENU_PARTY" },
+  },
+  gen2ItemEffects = {
+    MOD_ITEM = {
+      action = "heal", field = true, needsTarget = true,
+      use = function(ctx)
+        local mon = ctx.mon
+        if mon.hp >= mon.maxHp then
+          return { used = false, text = "It won't have\nany effect." }
+        end
+        mon.hp = math.min(mon.maxHp, mon.hp + 5)
+        return { used = true, text = "MOD ITEM used!" }
+      end,
+    },
   },
   gen2MenuGfx = {},
   gen2Icons = {
@@ -461,6 +479,24 @@ do
   eq(host.save.inventory.HP_UP, nil, "and the HP UP was spent")
 end
 
+do
+  -- #8 regression: Game2:usePartyItem asked ItemEffects.partyAction for the
+  -- item's family with no `data` argument, so it could only ever see
+  -- RECORDS -- the module's own built-ins.  A mod's field item, whose
+  -- action exists only in the merged gen2ItemEffects table, resolved to a
+  -- nil action and fell straight through to the "isn't going to help here"
+  -- refusal instead of opening the party list at all.
+  local mon = fixtureMon(12, { hp = 10 })
+  local host = newHost({ MOD_ITEM = 1 }, { mon })
+  host:useFieldItem("MOD_ITEM")
+  local party = host.stack:top()
+  check(party ~= nil and party.prompt ~= nil,
+    "a mod's own gen2ItemEffects record opens the party list")
+  drive(host, function() return host.stack:top() ~= party end)
+  eq(mon.hp, 15, "the mod item's own use() ran through the real menu")
+  eq(host.save.inventory.MOD_ITEM, nil, "and the mod item was spent")
+end
+
 do
   local mon = fixtureMon(12, { statExp = {
     hp = 25600, attack = 0, defense = 0, speed = 0, special = 0 } })