test(session): cover unknown-notification no-response and method-set extraction

Author: Ranga-Prasath-22

tests/server/test_session.py

@@ -564,15 +564,16 @@ async def mock_client():
         assert resp1.message.root.error.code == types.METHOD_NOT_FOUND
         assert resp1.message.root.error.message == "Method not found"
 
-        # 2. Send malformed known method request (initialize with invalid params shape)
+        # 2. Send malformed known method request (initialize missing required capabilities/clientInfo)
         await client_to_server_send.send(
             SessionMessage(
                 types.JSONRPCMessage(
                     types.JSONRPCRequest(
                         jsonrpc="2.0",
                         id=2,
                         method="initialize",
-                        params={"protocolVersion": 12345},  # invalid type for protocolVersion
+                        # protocolVersion is valid; capabilities/clientInfo are missing
+                        params={"protocolVersion": "2025-06-18"},
                     )
                 )
             )
@@ -593,3 +594,66 @@ async def mock_client():
     ):
         tg.start_soon(run_server)
         tg.start_soon(mock_client)
+
+
+@pytest.mark.anyio
+async def test_unknown_notification_receives_no_response():
+    """Test that unknown notifications go unanswered, per JSON-RPC (notifications must not be responded to)."""
+    server_to_client_send, server_to_client_receive = anyio.create_memory_object_stream[SessionMessage](1)
+    client_to_server_send, client_to_server_receive = anyio.create_memory_object_stream[SessionMessage | Exception](1)
+
+    async def run_server():
+        async with ServerSession(
+            client_to_server_receive,
+            server_to_client_send,
+            InitializationOptions(
+                server_name="mcp",
+                server_version="0.1.0",
+                capabilities=ServerCapabilities(),
+            ),
+        ):
+            await anyio.sleep(0.2)
+
+    async def mock_client():
+        # 1. Send an unknown notification
+        await client_to_server_send.send(
+            SessionMessage(
+                types.JSONRPCMessage(
+                    types.JSONRPCNotification(
+                        jsonrpc="2.0",
+                        method="totally/bogus",
+                        params={},
+                    )
+                )
+            )
+        )
+
+        # 2. Send a request afterwards; the first response received must be for the
+        # request, proving the notification produced no response
+        await client_to_server_send.send(
+            SessionMessage(
+                types.JSONRPCMessage(
+                    types.JSONRPCRequest(
+                        jsonrpc="2.0",
+                        id=1,
+                        method="totally/bogus",
+                        params={},
+                    )
+                )
+            )
+        )
+
+        resp = await server_to_client_receive.receive()
+        assert isinstance(resp.message.root, types.JSONRPCError)
+        assert resp.message.root.id == 1
+        assert resp.message.root.error.code == types.METHOD_NOT_FOUND
+
+    async with (
+        client_to_server_send,
+        client_to_server_receive,
+        server_to_client_send,
+        server_to_client_receive,
+        anyio.create_task_group() as tg,
+    ):
+        tg.start_soon(run_server)
+        tg.start_soon(mock_client)

tests/shared/test_session.py

@@ -23,6 +23,7 @@
     JSONRPCMessage,
     JSONRPCRequest,
     JSONRPCResponse,
+    ServerRequest,
     TextContent,
 )
 
@@ -395,3 +396,39 @@ class BrokenRequest(metaclass=ExplodingMeta):
         pass
 
     assert _extract_known_request_methods(BrokenRequest) == frozenset()
+
+
+def test_extract_known_request_methods_returns_full_client_and_server_method_sets():
+    assert _extract_known_request_methods(ClientRequest) == frozenset(
+        {
+            "completion/complete",
+            "initialize",
+            "logging/setLevel",
+            "ping",
+            "prompts/get",
+            "prompts/list",
+            "resources/list",
+            "resources/read",
+            "resources/subscribe",
+            "resources/templates/list",
+            "resources/unsubscribe",
+            "tasks/cancel",
+            "tasks/get",
+            "tasks/list",
+            "tasks/result",
+            "tools/call",
+            "tools/list",
+        }
+    )
+    assert _extract_known_request_methods(ServerRequest) == frozenset(
+        {
+            "elicitation/create",
+            "ping",
+            "roots/list",
+            "sampling/createMessage",
+            "tasks/cancel",
+            "tasks/get",
+            "tasks/list",
+            "tasks/result",
+        }
+    )