Merge pull request #205 from modelcontextprotocol/issue-192-request-id-test

Add test to verify request ID preservation

Author: dsp-ant

tests/issues/test_192_request_id.py

@@ -0,0 +1,88 @@
+import anyio
+import pytest
+
+from mcp.server.lowlevel import NotificationOptions, Server
+from mcp.server.models import InitializationOptions
+from mcp.types import (
+    LATEST_PROTOCOL_VERSION,
+    ClientCapabilities,
+    Implementation,
+    InitializeRequestParams,
+    JSONRPCMessage,
+    JSONRPCNotification,
+    JSONRPCRequest,
+    NotificationParams,
+)
+
+
+@pytest.mark.anyio
+async def test_request_id_match() -> None:
+    """Test that the server preserves request IDs in responses."""
+    server = Server("test")
+    custom_request_id = "test-123"
+
+    # Create memory streams for communication
+    client_writer, client_reader = anyio.create_memory_object_stream(1)
+    server_writer, server_reader = anyio.create_memory_object_stream(1)
+
+    # Server task to process the request
+    async def run_server():
+        async with client_reader, server_writer:
+            await server.run(
+                client_reader,
+                server_writer,
+                InitializationOptions(
+                    server_name="test",
+                    server_version="1.0.0",
+                    capabilities=server.get_capabilities(
+                        notification_options=NotificationOptions(),
+                        experimental_capabilities={},
+                    ),
+                ),
+                raise_exceptions=True,
+            )
+
+    # Start server task
+    async with anyio.create_task_group() as tg:
+        tg.start_soon(run_server)
+
+        # Send initialize request
+        init_req = JSONRPCRequest(
+            id="init-1",
+            method="initialize",
+            params=InitializeRequestParams(
+                protocolVersion=LATEST_PROTOCOL_VERSION,
+                capabilities=ClientCapabilities(),
+                clientInfo=Implementation(name="test-client", version="1.0.0"),
+            ).model_dump(by_alias=True, exclude_none=True),
+            jsonrpc="2.0",
+        )
+
+        await client_writer.send(JSONRPCMessage(root=init_req))
+        await server_reader.receive()  # Get init response but don't need to check it
+
+        # Send initialized notification
+        initialized_notification = JSONRPCNotification(
+            method="notifications/initialized",
+            params=NotificationParams().model_dump(by_alias=True, exclude_none=True),
+            jsonrpc="2.0",
+        )
+        await client_writer.send(JSONRPCMessage(root=initialized_notification))
+
+        # Send ping request with custom ID
+        ping_request = JSONRPCRequest(
+            id=custom_request_id, method="ping", params={}, jsonrpc="2.0"
+        )
+
+        await client_writer.send(JSONRPCMessage(root=ping_request))
+
+        # Read response
+        response = await server_reader.receive()
+
+        # Verify response ID matches request ID
+        assert (
+            response.root.id == custom_request_id
+        ), "Response ID should match request ID"
+
+        # Cancel server task
+        tg.cancel_scope.cancel()