Files
transcience/tests/unit/test_net_codec.gd
T
claude d8197885ca
ci / verify (push) Successful in 46s
Hide dead characters, suggest names, make the XP bar live
The roster sent to clients now contains living characters only. Retirement stays
server-side bookkeeping for archival; from the player's side a dead character is
simply gone, and listing it offers a choice that cannot be taken.

The XP bar only moved on a level-up or a character swap because it read the
character roster, which is re-sent only when the SET of characters changes.
Experience now rides the snapshot -- four bytes on a message already going out
at 20Hz -- and the server mirrors each grant into the world immediately rather
than only when a level is crossed.

The create field starts with a suggested name instead of blank, and offers
another after each creation.

Two bugs found while testing, both mine:

The first was a bad patch of my own: a change meant for the snapshot decoder
also matched inside decode_characters, which then read a four-byte field its
encoder never wrote and ran off the end of every packet. This is precisely the
"encodes but decodes wrong" failure the codec tests exist to catch, and it was
caught within a minute of the test being written.

Chasing that exposed a real robustness gap: StreamPeerBuffer.get_utf8_string()
pushes an engine error and returns garbage when the buffer is short, so a
truncated or hostile character/roster packet produced error spam instead of
degrading. Both decoders now bounds-check every field, with tests that slice
each packet at many lengths and assert it degrades rather than inventing
entries -- the same guarantee the input decoder already had.

206 tests. check.sh, test.sh, smoke.sh and both diagnostics pass.
2026-09-04 01:12:53 +02:00

274 lines
11 KiB
GDScript

extends GutTest
## Codec round-trips. A field that encodes but decodes wrong shows up as a
## mysterious gameplay bug three layers away, so it is pinned down here.
var world: SimWorld
func before_each() -> void:
world = SimWorld.new(7)
var p := world.add_player(42, "ada")
p.pos = Vector2(120.5, -64.25)
p.aim = 1.25
p.hp = 73
p.escape_ticks = 30
p.last_input_tick = 555
world.spawn_enemy(Content.turret(), Vector2(-200.0, 100.0))
world.spawn_boss(Content.warden())
world.tick = 9001
func test_snapshot_round_trips_player_state() -> void:
var snap := NetCodec.decode_snapshot(NetCodec.encode_snapshot(world))
assert_eq(int(snap["tick"]), 9001)
var rec: Dictionary = snap["players"][0]
assert_eq(int(rec["peer"]), 42)
assert_almost_eq((rec["pos"] as Vector2).x, 120.5, 0.01)
assert_almost_eq((rec["pos"] as Vector2).y, -64.25, 0.01)
assert_almost_eq(float(rec["aim"]), 1.25, 0.001)
assert_eq(int(rec["hp"]), 73)
assert_eq(int(rec["last_input_tick"]), 555)
assert_true((int(rec["flags"]) & Protocol.F_ALIVE) != 0)
assert_true((int(rec["flags"]) & Protocol.F_ESCAPING) != 0)
assert_almost_eq(float(rec["escape"]), 30.0 / float(SimConfig.ESCAPE_CHANNEL_TICKS), 0.01)
func test_snapshot_carries_enemy_radius_for_late_joiners() -> void:
var snap := NetCodec.decode_snapshot(NetCodec.encode_snapshot(world))
var e: Dictionary = snap["enemies"][0]
assert_almost_eq(float(e["radius"]), Content.turret().radius, 0.5)
assert_eq(int(e["visual"]), Content.turret().visual)
func test_snapshot_carries_the_boss() -> void:
var snap := NetCodec.decode_snapshot(NetCodec.encode_snapshot(world))
assert_not_null(snap["boss"])
assert_eq(int(snap["boss"]["hp"]), Content.warden().max_hp)
func test_dead_enemies_are_not_sent() -> void:
for e in world.enemies.values():
e.alive = false
var snap := NetCodec.decode_snapshot(NetCodec.encode_snapshot(world))
assert_eq((snap["enemies"] as Array).size(), 0)
func test_event_round_trip_preserves_bullet_spawn() -> void:
var ev := {
"t": SimEvent.Type.BULLET_SPAWN, "uid": 8123,
"pos": Vector2(10.0, -20.0), "vel": Vector2(0.0, 150.0),
"r": 7.5, "life": 300, "kind": SimConfig.KIND_NEEDLE,
"team": SimConfig.TEAM_ENEMY, "accel": 12.0, "turn": 0.02,
}
var packet := NetCodec.decode_events(NetCodec.encode_events(77, [ev]))
assert_eq(int(packet["tick"]), 77)
var out: Dictionary = packet["events"][0]
assert_eq(int(out["uid"]), 8123)
assert_eq(out["pos"], Vector2(10.0, -20.0))
assert_eq(out["vel"], Vector2(0.0, 150.0))
assert_almost_eq(float(out["r"]), 7.5, 0.001)
assert_eq(int(out["life"]), 300)
assert_almost_eq(float(out["accel"]), 12.0, 0.001)
assert_almost_eq(float(out["turn"]), 0.02, 0.0001)
func test_server_only_events_never_reach_the_wire() -> void:
var events: Array[Dictionary] = [
{"t": SimEvent.Type.PORTAL_USED, "peer": 3},
{"t": SimEvent.Type.ESCAPE_COMPLETED, "peer": 3},
{"t": SimEvent.Type.PLAYER_DIED, "peer": 3},
]
var packet := NetCodec.decode_events(NetCodec.encode_events(1, events))
assert_eq((packet["events"] as Array).size(), 1,
"instance transfers are the server's business, not the client's")
assert_eq(int(packet["events"][0]["t"]), SimEvent.Type.PLAYER_DIED)
func test_input_round_trip() -> void:
var frames: Array[InputFrame] = [
InputFrame.make(10, Vector2(1, 0), 0.0, InputFrame.BTN_FIRE),
InputFrame.make(11, Vector2(0, 1), 1.0, 0),
]
var out := NetCodec.decode_inputs(NetCodec.encode_inputs(frames))
assert_eq(out.size(), 2)
assert_eq(out[0].tick, 10)
assert_eq(out[1].tick, 11)
func test_truncated_input_packet_is_rejected_not_read_past() -> void:
var frames: Array[InputFrame] = [InputFrame.make(10, Vector2.ONE, 0.0, 1)]
var data := NetCodec.encode_inputs(frames)
# Claim three frames but send one. A hostile client will try exactly this.
data[0] = 3
assert_eq(NetCodec.decode_inputs(data).size(), 0)
func test_empty_input_packet_is_safe() -> void:
assert_eq(NetCodec.decode_inputs(PackedByteArray()).size(), 0)
# --- Roster -----------------------------------------------------------------
func test_roster_round_trips() -> void:
var entries: Array[Dictionary] = [
{"peer": 7, "name": "ada", "kind": Protocol.InstanceKind.LOBBY,
"instance": 1, "alive": true},
{"peer": 9, "name": "grace", "kind": Protocol.InstanceKind.DUNGEON,
"instance": 4, "alive": false},
]
var out := NetCodec.decode_roster(NetCodec.encode_roster(entries))
assert_eq(out.size(), 2)
assert_eq(int(out[0]["peer"]), 7)
assert_eq(String(out[0]["name"]), "ada")
assert_eq(int(out[0]["kind"]), Protocol.InstanceKind.LOBBY)
assert_true(out[0]["alive"])
assert_eq(String(out[1]["name"]), "grace")
assert_eq(int(out[1]["kind"]), Protocol.InstanceKind.DUNGEON,
"the hub needs to know someone is already inside")
assert_eq(int(out[1]["instance"]), 4)
assert_false(out[1]["alive"])
func test_roster_survives_unicode_names() -> void:
var entries: Array[Dictionary] = [
{"peer": 1, "name": "ゆき", "kind": 0, "instance": 1, "alive": true}]
var out := NetCodec.decode_roster(NetCodec.encode_roster(entries))
assert_eq(String(out[0]["name"]), "ゆき")
func test_empty_roster_is_safe() -> void:
assert_eq(NetCodec.decode_roster(PackedByteArray()).size(), 0)
assert_eq(NetCodec.decode_roster(NetCodec.encode_roster([] as Array[Dictionary])).size(), 0)
# --- Snapshot extras --------------------------------------------------------
func test_snapshot_carries_spawn_grace_and_linkdead_flags() -> void:
var p: SimPlayer = world.players[42]
p.spawn_grace = 30
p.linkdead = true
var snap := NetCodec.decode_snapshot(NetCodec.encode_snapshot(world))
var flags := int(snap["players"][0]["flags"])
assert_true((flags & Protocol.F_SPAWN_GRACE) != 0)
assert_true((flags & Protocol.F_LINKDEAD) != 0)
func test_cleared_countdown_round_trips() -> void:
var snap := NetCodec.decode_snapshot(NetCodec.encode_snapshot(world, 17))
assert_eq(int(snap["cleared_countdown"]), 17)
func test_countdown_defaults_to_not_applicable() -> void:
var snap := NetCodec.decode_snapshot(NetCodec.encode_snapshot(world))
assert_eq(int(snap["cleared_countdown"]), Protocol.COUNTDOWN_NONE)
# --- Characters -------------------------------------------------------------
func test_character_roster_round_trips() -> void:
var rng := RandomNumberGenerator.new()
rng.seed = 5
var a := Character.create("Ada", rng)
a.grant_xp(Progression.total_xp_for_level(4))
var b := Character.create("Second", rng)
var out := NetCodec.decode_characters(
NetCodec.encode_characters([a, b] as Array[Character], a.id))
assert_eq(String(out["selected"]), a.id)
var chars: Array = out["characters"]
assert_eq(chars.size(), 2)
assert_eq(String(chars[0]["name"]), "Ada")
assert_eq(int(chars[0]["level"]), a.level)
assert_eq(int(chars[0]["max_hp"]), a.max_hp(),
"the roster shows each character's own health ceiling")
assert_true(chars[0]["active"])
## Colour is a character's only identity until cosmetics exist, so it has to
## survive the wire exactly rather than approximately.
func test_character_colour_survives_the_wire() -> void:
var rng := RandomNumberGenerator.new()
rng.seed = 11
var c := Character.create("Hue", rng)
var out := NetCodec.decode_characters(
NetCodec.encode_characters([c] as Array[Character], ""))
var got: Color = out["characters"][0]["colour"]
assert_eq(got.to_rgba32(), c.colour.to_rgba32())
func test_an_empty_character_list_is_safe() -> void:
var out := NetCodec.decode_characters(
NetCodec.encode_characters([] as Array[Character], ""))
assert_eq((out["characters"] as Array).size(), 0)
assert_eq(NetCodec.decode_characters(PackedByteArray())["characters"].size(), 0)
## Max health is per-character now, so a snapshot that assumed a constant would
## draw every levelled player's bar wrong.
func test_the_snapshot_carries_each_players_own_max_health() -> void:
var p: SimPlayer = world.players[42]
p.level = 5
p.max_hp = Progression.max_hp_for_level(5)
p.hp = 42
p.colour = Color(0.2, 0.6, 0.9)
var snap := NetCodec.decode_snapshot(NetCodec.encode_snapshot(world))
var rec: Dictionary = snap["players"][0]
assert_eq(int(rec["hp"]), 42)
assert_eq(int(rec["max_hp"]), Progression.max_hp_for_level(5))
assert_almost_eq((rec["colour"] as Color).b, 0.9, 0.02,
"party members are told apart by colour, so it rides the snapshot")
## The bar has to move on every kill, so experience rides the snapshot rather
## than waiting for a roster message that is only sent when the SET of
## characters changes.
func test_the_snapshot_carries_live_experience() -> void:
var p: SimPlayer = world.players[42]
p.total_xp = 1234
var snap := NetCodec.decode_snapshot(NetCodec.encode_snapshot(world))
assert_eq(int(snap["players"][0]["total_xp"]), 1234)
## The failure mode this file exists for, made explicit. A decoder that reads a
## field its encoder never wrote runs off the end of the buffer -- which is what
## happened when a snapshot change was applied to the character decoder by
## mistake.
func test_a_truncated_character_packet_does_not_read_past_the_end() -> void:
var rng := RandomNumberGenerator.new()
rng.seed = 21
var full := NetCodec.encode_characters(
[Character.create("Ada", rng), Character.create("Bee", rng)] as Array[Character], "")
for cut in [1, 4, 9, 17, 25, 33]:
if cut >= full.size():
continue
var out := NetCodec.decode_characters(full.slice(0, cut))
assert_lte((out["characters"] as Array).size(), 2,
"a packet cut at %d bytes must degrade, not invent entries" % cut)
func test_the_character_decoder_consumes_exactly_what_the_encoder_wrote() -> void:
var rng := RandomNumberGenerator.new()
rng.seed = 22
var chars := [Character.create("Solo", rng)] as Array[Character]
var data := NetCodec.encode_characters(chars, "")
# Append a sentinel: if the decoder reads the right number of bytes, the
# sentinel is untouched and the entry still decodes cleanly.
var padded := data.duplicate()
padded.append_array(PackedByteArray([0xAB, 0xCD]))
var out := NetCodec.decode_characters(padded)
assert_eq((out["characters"] as Array).size(), 1)
assert_eq(String(out["characters"][0]["name"]), "Solo")
## Truncation safety for the other string-carrying message, for the same reason.
func test_a_truncated_roster_packet_does_not_read_past_the_end() -> void:
var entries: Array[Dictionary] = [
{"peer": 1, "name": "someone", "kind": 0, "instance": 1, "alive": true},
{"peer": 2, "name": "another", "kind": 1, "instance": 3, "alive": true},
]
var full := NetCodec.encode_roster(entries)
for cut in range(1, full.size(), 3):
var out := NetCodec.decode_roster(full.slice(0, cut))
assert_lte(out.size(), 2,
"a roster cut at %d bytes must degrade, not invent entries" % cut)
assert_eq(NetCodec.decode_roster(full).size(), 2, "and the full packet still works")