CLOSES #1211, CLOSES #1228, CLOSES #1229, CLOSES #1232, CLOSES #1251, CLOSES #1265, CLOSES #1267, CLOSES #1276, CLOSES #1279, CLOSES #1282, CLOSES #1293, CLOSES #1296, CLOSES #1303, CLOSES #1329, CLOSES #1338, CLOSES #1341, CLOSES #1343, CLOSES #1344, CLOSES #1368, CLOSES #1385, CLOSES #1388, CLOSES #1389, CLOSES #1391

tests/engine/npc_walk_cadence_bug1303.lua

@@ -0,0 +1,96 @@
+-- The walking-NPC animation cadence, which the port ran at half the cart's
+-- rate (#1303).  UpdateSpriteInWalkingAnimation advances one animation frame
+-- every 4 fixed steps regardless of how long the whole cell takes
+-- (engine/overworld/movement.asm:301), so a 32-frame NPC cell must show the
+-- same two-pulse cadence Player:pose already shows across its own 16.
+--   luajit tests/engine/npc_walk_cadence_bug1303.lua
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+
+love = require("tests.love_stub")
+
+local NPC = require("src.world.NPC")
+
+local DATA = {
+  sprites = {
+    SPRITE_TEST_NPC = { image = "fixture_npc.png", frames = 6, walker = true },
+  },
+}
+
+local function newNpc()
+  return NPC.new(DATA, "TEST_MAP", {
+    index = 1, x = 5, y = 5, sprite = "SPRITE_TEST_NPC", range = "ANY_DIR",
+    movement = "STAY",
+  })
+end
+
+-- ---- the pure cadence: two walk pulses across one 32-frame NPC step ------
+do
+  local npc = newNpc()
+  npc.moving = true
+  local phases = {}
+  for clock = 0, 31 do
+    npc.animClock = clock
+    phases[clock] = npc:walkPhase()
+  end
+  local risingEdges = 0
+  for clock = 1, 31 do
+    if phases[clock] == 1 and phases[clock - 1] == 0 then
+      risingEdges = risingEdges + 1
+    end
+  end
+  eq(risingEdges, 2, "a 32-frame NPC cell shows two walk pulses, not one")
+  eq(phases[0], 0, "frame 0 stands")
+  eq(phases[4], 1, "frame 4 opens the first walk pulse")
+  eq(phases[11], 1, "frame 11 is still the first pulse")
+  eq(phases[12], 0, "frame 12 closes it back to standing")
+  eq(phases[20], 1, "frame 20 opens the second walk pulse")
+  eq(phases[27], 1, "frame 27 is still the second pulse")
+  eq(phases[28], 0, "frame 28 closes the cycle back to standing")
+end
+
+-- ---- the flip half-cycle: one flip per 16-frame half, not per whole cell -
+do
+  local npc = newNpc()
+  npc.moving = true
+  npc.animClock = 0
+  local _, _, _, _, _, flip0 = npc:pose()
+  npc.animClock = 15
+  local _, _, _, _, _, flip15 = npc:pose()
+  npc.animClock = 16
+  local _, _, _, _, _, flip16 = npc:pose()
+  npc.animClock = 31
+  local _, _, _, _, _, flip31 = npc:pose()
+  check(not flip0, "the first half of the cell is unflipped")
+  check(not flip15, "still unflipped just before frame 16")
+  check(flip16, "frame 16 flips, matching Player:pose's own half-cycle")
+  check(flip31, "and stays flipped through the second half")
+end
+
+-- ---- standing keeps the externally-written flip (Pikachu idle contract) --
+do
+  local npc = newNpc()
+  npc.moving = false
+  npc.stepFlip = true
+  local _, _, _, _, phase, flip = npc:pose()
+  eq(phase, 0, "a standing NPC has no walk phase")
+  check(flip, "and pose() reads stepFlip back exactly, not the moving formula")
+end
+
+-- ---- the wiring: NPC:update advances animClock alongside progress -------
+do
+  local npc = newNpc()
+  npc.facing = "down"
+  npc.moving = true
+  npc.targetX, npc.targetY = npc.cellX, npc.cellY + 1
+  local map = {}
+  for i = 1, 16 do
+    npc:update(map, {})
+    eq(npc.animClock, i, "animClock ticks once per update, step " .. i)
+  end
+  check(npc.moving, "still mid-cell at 16 of the 32 ticks")
+end
+
+T.finish("npc walk cadence bug1303")