extends GutTest
## Invariants every piece of content has to satisfy. These are cheap to write
## and they are what stops a new enemy from quietly reintroducing a mechanic the
## game has decided against.

const HOSTILES := [
	Content.ENEMY_DRIFTER,
	Content.ENEMY_TURRET,
	Content.ENEMY_STALKER,
]


## The rule: nothing in this game hurts you by touching you. Every threat is a
## bullet you can see and dodge, so an enemy with no emitters is either inert
## scenery or a design mistake.
func test_every_hostile_enemy_actually_fires_something() -> void:
	for id in HOSTILES:
		var def := Content.enemy(id)
		assert_gt(def.emitters.size(), 0,
			"%s has no emitters -- it would be a harmless obstacle" % id)


func test_the_practice_dummy_is_inert() -> void:
	var def := Content.enemy(Content.ENEMY_DUMMY)
	assert_eq(def.emitters.size(), 0, "the hub target must never shoot back")


## Standing inside an enemy costs nothing by itself. Uses the dummy so the test
## measures contact alone, with no bullets in play to confuse the result.
func test_touching_an_enemy_deals_no_damage() -> void:
	var world := SimWorld.new(1)
	var p := world.add_player(1, "tester")
	var e := world.spawn_enemy(Content.dummy(), Vector2.ZERO)
	p.pos = e.pos
	p.spawn_grace = 0
	for _i in 120:
		world.step()
	assert_eq(p.hp, SimConfig.PLAYER_MAX_HP,
		"contact damage is not a damage type in this game")


## The Stalker's burst replaces its old contact damage, so it has to be a real
## threat once it closes -- and harmless from across the arena.
func test_the_stalker_threatens_at_point_blank_only() -> void:
	var near := SimWorld.new(1)
	var pn := near.add_player(1, "tester")
	pn.pos = Vector2.ZERO
	pn.spawn_grace = 0
	near.spawn_enemy(Content.stalker(), Vector2(40.0, 0.0))
	for _i in 90:
		near.step()
	assert_lt(pn.hp, SimConfig.PLAYER_MAX_HP, "point blank has to hurt")

	var far := SimWorld.new(1)
	var pf := far.add_player(1, "tester")
	pf.pos = Vector2(0.0, 300.0)
	pf.spawn_grace = 0
	# Pinned in place so it cannot close the distance during the test.
	var e := far.spawn_enemy(Content.stalker(), Vector2(0.0, -300.0))
	e.def = Content.stalker()
	e.def.speed = 0.0
	for _i in 90:
		far.step()
	assert_eq(pf.hp, SimConfig.PLAYER_MAX_HP,
		"its bullets must expire long before they cross the arena")


func test_enemy_bullets_from_the_stalker_do_not_litter_the_arena() -> void:
	var world := SimWorld.new(1)
	var p := world.add_player(1, "tester")
	p.pos = Vector2(0.0, 300.0)
	var e := world.spawn_enemy(Content.stalker(), Vector2(0.0, -300.0))
	e.def = Content.stalker()
	e.def.speed = 0.0
	for _i in 300:
		world.step()
	assert_lt(world.pool.live_count, 12,
		"a short lifetime should keep spent point-blank shots from accumulating")