Track gas bomb cooldowns per bomber

tests/test_gas_bomber_cooldowns.gd

@@ -0,0 +1,65 @@
+extends SceneTree
+
+var main: Node
+var fleet: Node
+var skill: GasBombController
+var elapsed := 0.0
+
+
+func _initialize() -> void:
+	var state: Node = root.get_node("GameState")
+	state.buildings.clear()
+	state.extractors.clear()
+	state.transporters.clear()
+	state.vessel_levels["unlock_gas_bomber"] = 1
+	main = load("res://Main.tscn").instantiate()
+	root.add_child(main)
+	fleet = main.get_node("Fleet")
+	skill = main.get_node("GasBombController")
+
+
+func _process(delta: float) -> bool:
+	elapsed += delta
+	if elapsed < 0.2:
+		return false
+	main.get_node("EnemySpawner").set_process(false)
+	main.get_node("AsteroidField").set_process(false)
+	fleet.spawn_ships(2, Vector2.ZERO, PackedStringArray([
+		GameState.VESSEL_GAS_BOMBER, GameState.VESSEL_GAS_BOMBER]))
+	skill._process(0.0)
+	var first: Node = fleet.ships[0].get_component("gas_bomber")
+	var second: Node = fleet.ships[1].get_component("gas_bomber")
+	if not first.is_ready() or not second.is_ready() or not skill.button.enabled:
+		return _fail("two fresh bombers did not each begin ready")
+
+	skill.aim_target = Vector2(500, 0)
+	skill._fire()
+	skill._process(0.0)
+	if first.is_ready() or not second.is_ready() or not skill.button.enabled:
+		return _fail("the first shot disabled more than its firing bomber")
+	if skill.projectiles.size() != 1:
+		return _fail("the first bomber did not launch exactly one projectile")
+
+	skill.aim_target = Vector2(-500, 0)
+	skill._fire()
+	skill._process(0.0)
+	if first.is_ready() or second.is_ready() or skill.button.enabled:
+		return _fail("the skill stayed available after both bombers fired")
+	if skill.projectiles.size() != 2:
+		return _fail("independent bombers could not have shots in flight together")
+
+	# Rearming one bomber restores one available shot without touching the
+	# other bomber's cooldown.
+	first.tick(GasBombController.COOLDOWN)
+	skill._process(0.0)
+	if not first.is_ready() or second.is_ready() or not skill.button.enabled:
+		return _fail("one completed cooldown did not restore exactly one shot")
+	print("TEST_GAS_BOMBER_COOLDOWNS: PASS")
+	quit(0)
+	return true
+
+
+func _fail(message: String) -> bool:
+	print("TEST_GAS_BOMBER_COOLDOWNS: FAIL (%s)" % message)
+	quit(1)
+	return true