✅ test(@projects/@magic-civilization): ✨ add end-to-end ai promotion gut test

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

src/game/engine/tests/integration/test_p2_44_ai_promotion_end_to_end.gd

@@ -0,0 +1,120 @@
+extends GutTest
+## p2-44 — End-to-end GUT verification that AI-owned units promote and that
+## the `EventBus.unit_promoted` signal fires through the live dispatch path.
+##
+## Headless-compatible: no rendering, no UI. Drives the dispatch entry point
+## directly with a synthetic `PromotionPicked` action JSON, mirroring the
+## same envelope `AiTurnBridge` ships from Rust. Asserts:
+##   1. `unit.promote(promo_id)` applied (veteran_level += 1, promo_ids += id)
+##   2. `EventBus.unit_promoted` emitted exactly once with (unit, promo_id)
+##   3. `dispatch_action` returns true for the PromotionPicked variant
+##
+## This locks the GDScript half of the p2-44 chain — the Rust picker side is
+## covered by 5 unit tests in `mc-ai::tactical::promotion::tests`. The full
+## chain (build_tactical_state -> Rust pick_promotion -> dispatch) is gated
+## by the apricot 10-seed batch counting `unit_promoted` rows in events.jsonl.
+
+const UnitScript: GDScript = preload("res://engine/src/entities/unit.gd")
+const DispatchScript: GDScript = preload(
+	"res://engine/src/modules/ai/ai_turn_bridge_dispatch.gd"
+)
+
+var _emitted: Array[Dictionary] = []
+
+
+func before_each() -> void:
+	_emitted = []
+	if EventBus.unit_promoted.is_connected(_on_unit_promoted):
+		EventBus.unit_promoted.disconnect(_on_unit_promoted)
+	EventBus.unit_promoted.connect(_on_unit_promoted)
+
+
+func after_each() -> void:
+	if EventBus.unit_promoted.is_connected(_on_unit_promoted):
+		EventBus.unit_promoted.disconnect(_on_unit_promoted)
+
+
+func _on_unit_promoted(unit: Variant, promotion: String) -> void:
+	_emitted.append({"unit": unit, "promotion": promotion})
+
+
+func _make_ai_unit(uid: int) -> Unit:
+	var unit: Unit = UnitScript.new("dwarf_warrior", 0, Vector2i(3, 3))
+	unit.id = "ai_unit_%d" % uid
+	unit.hp = 10
+	unit.max_hp = 10
+	unit.xp = 12
+	unit.veteran_level = 0
+	return unit
+
+
+func test_dispatch_promotion_picked_promotes_and_emits() -> void:
+	# Arrange — synthetic AI unit eligible for tier-1 promotion.
+	var unit: Unit = _make_ai_unit(7)
+	var index_maps: Dictionary = {"units": {7: unit}, "cities": {}}
+	var prev_level: int = unit.veteran_level
+	var action_str: String = JSON.stringify({
+		"PromotionPicked": {"unit_id": 7, "promotion_id": "shock"},
+	})
+
+	# Act — drive the same entry point AiTurnBridge uses on AI turns.
+	var ok: bool = DispatchScript.dispatch_action(
+		action_str, null, index_maps, ""
+	)
+
+	# Assert — return value, mutation, signal.
+	assert_true(ok, "dispatch_action should accept PromotionPicked variant")
+	assert_eq(
+		unit.veteran_level, prev_level + 1,
+		"veteran_level must increment on dispatch"
+	)
+	assert_true(
+		unit.promo_ids.has("shock"),
+		"promo_ids must contain the picked promotion"
+	)
+	assert_eq(
+		_emitted.size(), 1,
+		"EventBus.unit_promoted must fire exactly once per dispatch"
+	)
+	if _emitted.size() == 1:
+		assert_eq(
+			_emitted[0]["promotion"], "shock",
+			"signal payload promotion id must match dispatched id"
+		)
+		assert_eq(
+			_emitted[0]["unit"], unit,
+			"signal payload unit must be the same RefCounted instance"
+		)
+
+
+func test_dispatch_rejects_dead_unit() -> void:
+	# A dead AI unit must not promote — guards against late dispatch races.
+	var unit: Unit = _make_ai_unit(11)
+	unit.hp = 0
+	var index_maps: Dictionary = {"units": {11: unit}, "cities": {}}
+	var action_str: String = JSON.stringify({
+		"PromotionPicked": {"unit_id": 11, "promotion_id": "shock"},
+	})
+
+	var ok: bool = DispatchScript.dispatch_action(
+		action_str, null, index_maps, ""
+	)
+
+	assert_false(ok, "dispatch_action must reject dead-unit promotion")
+	assert_eq(unit.veteran_level, 0, "dead unit must not promote")
+	assert_eq(_emitted.size(), 0, "no signal must fire for dead-unit dispatch")
+
+
+func test_dispatch_rejects_empty_promotion_id() -> void:
+	var unit: Unit = _make_ai_unit(13)
+	var index_maps: Dictionary = {"units": {13: unit}, "cities": {}}
+	var action_str: String = JSON.stringify({
+		"PromotionPicked": {"unit_id": 13, "promotion_id": ""},
+	})
+
+	var ok: bool = DispatchScript.dispatch_action(
+		action_str, null, index_maps, ""
+	)
+
+	assert_false(ok, "empty promotion_id must be rejected")
+	assert_eq(_emitted.size(), 0, "no signal for empty promotion_id")