Add one-slot demo snapshot save and load.

tests/snapshot_smoke.gd

@@ -0,0 +1,126 @@
+extends SceneTree
+
+const WorldSimulation = preload("res://src/simulation/world_simulation.gd")
+const DemoSnapshot = preload("res://src/persistence/demo_snapshot.gd")
+const TEST_PATH := "user://mana_foundry_snapshot_test.json"
+
+
+func _initialize() -> void:
+	DemoSnapshot.path_override = TEST_PATH
+	if FileAccess.file_exists(TEST_PATH):
+		DirAccess.remove_absolute(ProjectSettings.globalize_path(TEST_PATH))
+
+	var failures: Array[String] = []
+	var live := _make_two_stage()
+	for _tick in range(400):
+		live.step()
+	var before := live.state_fingerprint()
+	var charged_before := live.get_charged_count()
+	var snapshot := live.to_snapshot()
+
+	var restored := WorldSimulation.new()
+	if not restored.apply_snapshot(snapshot):
+		failures.append("apply_snapshot rejected a live two-stage snapshot.")
+	elif restored.state_fingerprint() != before:
+		failures.append("Restored simulation fingerprint did not match the live factory.")
+	elif restored.get_charged_count() != charged_before:
+		failures.append("Restored charged count did not match.")
+
+	if failures.is_empty():
+		for _tick in range(200):
+			live.step()
+			restored.step()
+		if live.state_fingerprint() != restored.state_fingerprint():
+			failures.append("Live and restored factories diverged after more ticks.")
+
+	if not DemoSnapshot.save_payload({"schema": DemoSnapshot.SCHEMA, "simulation": snapshot}):
+		failures.append("DemoSnapshot could not write the test slot.")
+	else:
+		var loaded := DemoSnapshot.load_payload()
+		var from_disk := WorldSimulation.new()
+		if not from_disk.apply_snapshot(loaded.get("simulation", {})):
+			failures.append("Disk snapshot failed to apply.")
+		elif from_disk.state_fingerprint() != before:
+			failures.append("Disk snapshot fingerprint did not match the pre-save factory.")
+
+	var empty := WorldSimulation.new()
+	if empty.is_demo_complete():
+		failures.append("Empty factory reported demo complete.")
+	var first_item := _make_two_stage()
+	var saw_item := false
+	for _tick in range(2000):
+		first_item.step()
+		if first_item.get_charged_count() >= 1:
+			saw_item = true
+			break
+	if not saw_item:
+		failures.append("Two-stage factory never produced a charged crystal for the one-item check.")
+	elif first_item.is_demo_complete():
+		failures.append("Demo completed after a single charged crystal.")
+	else:
+		var mid := WorldSimulation.new()
+		if not mid.apply_snapshot(first_item.to_snapshot()):
+			failures.append("Could not restore the one-item factory.")
+		elif mid.is_demo_complete():
+			failures.append("Loaded one-item factory reported complete.")
+
+	var packed := load("res://scenes/main.tscn") as PackedScene
+	var demo := packed.instantiate()
+	root.add_child.call_deferred(demo)
+	await process_frame
+	await process_frame
+	demo.call("_start_new_game")
+	var sim: WorldSimulation = demo.get("simulation")
+	for x in range(-5, -1):
+		sim.place_building(WorldSimulation.KIND_BELT, Vector2i(x, 0), 0)
+	sim.place_building(WorldSimulation.KIND_BELT, Vector2i(0, 0), 0)
+	for x in range(2, 6):
+		sim.place_building(WorldSimulation.KIND_BELT, Vector2i(x, 0), 0)
+	for z in range(1, 5):
+		sim.place_building(WorldSimulation.KIND_MANA_PIPE, Vector2i(0, z), 1)
+	sim.configure_machine_bridge(int(demo.get("anchor_machine_id")), Vector2i(-2, 0), Vector2i(0, 0))
+	sim.configure_machine_bridge(int(demo.get("charger_machine_id")), Vector2i(0, 0), Vector2i(2, 0))
+	for _tick in range(240):
+		sim.step()
+	var scene_before := sim.state_fingerprint()
+	var payload: Dictionary = demo.call("collect_demo_snapshot")
+	if not bool(demo.call("_save_demo_snapshot")):
+		failures.append("Scene save helper failed.")
+	demo.call("_reset_demo")
+	if sim.state_fingerprint() == scene_before:
+		failures.append("Reset after save did not change simulation state.")
+	if not bool(demo.call("_load_demo_snapshot")):
+		failures.append("Scene load helper failed.")
+	elif sim.state_fingerprint() != scene_before:
+		failures.append("Scene save/load did not restore the simulation fingerprint.")
+
+	if FileAccess.file_exists(TEST_PATH):
+		DirAccess.remove_absolute(ProjectSettings.globalize_path(TEST_PATH))
+	DemoSnapshot.path_override = ""
+
+	if failures.is_empty():
+		print("SNAPSHOT_SMOKE_OK charged=%d fingerprint=%s" % [charged_before, before])
+		quit(0)
+	else:
+		for failure in failures:
+			push_error(failure)
+		quit(1)
+
+
+func _make_two_stage() -> WorldSimulation:
+	var simulation := WorldSimulation.new()
+	simulation.place_building(WorldSimulation.KIND_SOURCE, Vector2i(-6, 0), 0)
+	for x in range(-5, -1):
+		simulation.place_building(WorldSimulation.KIND_BELT, Vector2i(x, 0), 0)
+	simulation.place_building(WorldSimulation.KIND_BELT, Vector2i(0, 0), 0)
+	for x in range(2, 6):
+		simulation.place_building(WorldSimulation.KIND_BELT, Vector2i(x, 0), 0)
+	simulation.place_building(WorldSimulation.KIND_SINK, Vector2i(6, 0), 0)
+	var refine_id := simulation.place_building(WorldSimulation.KIND_MACHINE, Vector2i(-1, 1), 0)
+	var charger_id := simulation.place_building(WorldSimulation.KIND_CHARGER, Vector2i(1, 1), 0)
+	simulation.place_building(WorldSimulation.KIND_MANA_SOURCE, Vector2i(0, 5), 1)
+	for z in range(1, 5):
+		simulation.place_building(WorldSimulation.KIND_MANA_PIPE, Vector2i(0, z), 1)
+	simulation.configure_machine_bridge(refine_id, Vector2i(-2, 0), Vector2i(0, 0))
+	simulation.configure_machine_bridge(charger_id, Vector2i(0, 0), Vector2i(2, 0))
+	return simulation