Test GNS reliable send failure handling

server/tests/test_gns_gameplay_adapter.py

@@ -3,7 +3,9 @@ from __future__ import annotations
 import json
 from collections import deque
 
-from gns_gameplay_adapter import GnsGameplayAdapter
+import pytest
+
+from gns_gameplay_adapter import GnsConnectionAdapter, GnsGameplayAdapter
 from gns_transport import EventType, GnsEvent, RemoteEndpoint, SendResult
 from packet_codec import encode_packet
 from server_core import FalloutTogetherServer, PROTOCOL_VERSION
@@ -15,6 +17,7 @@ class FakeGnsTransport:
         self.events = deque()
         self.endpoints = {}
         self.sent = []
+        self.send_results = deque()
         self.disconnected = []
         self.closed = False
 
@@ -26,7 +29,7 @@ class FakeGnsTransport:
 
     def send_encoded(self, connection_id, encoded):
         self.sent.append((connection_id, encoded))
-        return SendResult.SENT
+        return self.send_results.popleft() if self.send_results else SendResult.SENT
 
     def send_packet(self, connection_id, packet):
         return self.send_encoded(connection_id, encode_packet(packet))
@@ -165,6 +168,25 @@ def test_gns_adapter_preserves_reliable_and_snapshot_delivery_policy():
     assert player_state_relays[-1].delivery is Delivery.RELIABLE_ORDERED
 
 
+def test_connection_adapter_may_drop_snapshots_but_never_reliable_messages_silently():
+    transport = FakeGnsTransport()
+    connection = GnsConnectionAdapter(transport, 250)
+
+    transport.send_results.append(SendResult.DROPPED)
+    connection.sendall(b'{"type":"transform","x":1}\n')
+
+    transport.send_results.append(SendResult.BACKPRESSURE)
+    connection.sendall(b'{"type":"npcState","npcs":[]}\n')
+
+    transport.send_results.append(SendResult.DROPPED)
+    with pytest.raises(OSError):
+        connection.sendall(b'{"type":"playerState","characterName":"Nomad"}\n')
+
+    transport.send_results.append(SendResult.BACKPRESSURE)
+    with pytest.raises(OSError):
+        connection.sendall(b'{"type":"combatHit","sequence":1}\n')
+
+
 def test_gns_adapter_enforces_existing_ban_policy(tmp_path):
     server = FalloutTogetherServer(host="127.0.0.1", port=0, bans_path=str(tmp_path / "bans.json"))
     server.ban_ip("127.0.0.1", "test ban")