Wolf den search steps into the valley when the rim is steep everywhere

tests/test_den_sites.gd

@@ -0,0 +1,42 @@
+extends SceneTree
+## Every island gets a wolf den: across many seeds the site search finds a
+## spot away from the spawn and the sea.
+## Run: godot --headless --path . --script res://tests/test_den_sites.gd
+
+const SEEDS := [777, 4, 1337, 1, 2, 3, 5, 6, 7, 8, 9, 10, 42, 99, 123, 2024, 4242, 9001, 31337, 65535]
+
+var _fails := 0
+
+func check(cond: bool, what: String) -> void:
+	print(("  ok   " if cond else "  FAIL ") + what)
+	if not cond:
+		_fails += 1
+
+func _initialize() -> void:
+	_run.call_deferred()
+
+func _run() -> void:
+	var S: Node = root.get_node("Saves")
+	S.root_dir = "user://test_den_sites"
+	for seed in SEEDS:
+		for w in S.list_worlds():
+			S.delete_world(w.id)
+		S.current_id = S.create_world("Den %d" % seed, seed)
+		var world: Node3D = load("res://scenes/world.tscn").instantiate()
+		root.add_child(world)
+		for _i in range(3):
+			await physics_frame
+		var den: Node3D = world.den
+		var t: Node3D = world.terrain
+		var p: Vector3 = den.position
+		var ok: bool = den.found
+		if ok:
+			ok = Vector2(p.x, p.z).length() >= 50.0 and t.sea_weight(p.x, p.z) <= 0.02
+		check(ok, "seed %d has a den (%.0f m from the centre)" % [seed, Vector2(p.x, p.z).length()])
+		world.queue_free()
+		await physics_frame
+	for w in S.list_worlds():
+		S.delete_world(w.id)
+	DirAccess.remove_absolute(S.root_dir)
+	print("RESULT: %s (%d failures)" % ["PASS" if _fails == 0 else "FAIL", _fails])
+	quit(1 if _fails > 0 else 0)