fix: resolve all ruff linting errors

- Fix line too long in proxy.py by extracting method name to variable

- Fix loop variable overwrite by sending transformed message directly

- Remove unused 'received' variables in tests

- All ruff checks now pass

Author: dgenio

src/mcp/shared/proxy.py

@@ -70,7 +70,8 @@ def log_error(error: Exception) -> None:
                 logger.error(f"Proxy error: {error}")
 
             async def inspect_client_msg(msg: SessionMessage) -> SessionMessage | None:
-                logger.info(f"Client → Server: {msg.message.root.method if hasattr(msg.message.root, 'method') else 'response'}")
+                method = msg.message.root.method if hasattr(msg.message.root, "method") else "response"
+                logger.info(f"Client → Server: {method}")
                 return msg  # Forward as-is
 
             async with mcp_proxy(
@@ -114,10 +115,11 @@ async def forward_messages(
                             # Message was dropped by the transform function
                             logger.debug(f"Message dropped by transform function in {direction}")
                             continue
-                        message = transformed
-
-                    # Forward the message
-                    await write_stream.send(message)
+                        # Use the transformed message instead
+                        await write_stream.send(transformed)
+                    else:
+                        # Forward the message as-is
+                        await write_stream.send(message)
 
                 except Exception as exc:
                     logger.exception(f"Error forwarding message in {direction}")

tests/shared/test_proxy.py

@@ -20,8 +20,19 @@ def _create():
         server_read_writer, server_read = anyio.create_memory_object_stream[SessionMessage | Exception](10)
         server_write, server_write_reader = anyio.create_memory_object_stream[SessionMessage](10)
 
-        # Track all streams for cleanup
-        streams_to_cleanup.extend([client_read_writer, client_write_reader, server_read_writer, server_write_reader])
+        # Track ALL 8 streams for cleanup (both send and receive ends of all 4 pairs)
+        streams_to_cleanup.extend(
+            [
+                client_read_writer,
+                client_read,
+                client_write,
+                client_write_reader,
+                server_read_writer,
+                server_read,
+                server_write,
+                server_write_reader,
+            ]
+        )
 
         return (
             (client_read, client_write),
@@ -185,7 +196,7 @@ async def drop_message(msg: SessionMessage) -> SessionMessage | None:
 
             # Message should not arrive at server
             with anyio.move_on_after(0.1):
-                received = await server_write_reader.receive()
+                await server_write_reader.receive()
                 # If we get here, the message was not dropped
                 pytest.fail("Message should have been dropped")
     finally:
@@ -290,7 +301,7 @@ async def failing_transform(msg: SessionMessage) -> SessionMessage | None:
 
             # Message should not arrive at server due to transform error
             with anyio.move_on_after(0.1):
-                received = await server_write_reader.receive()
+                await server_write_reader.receive()
                 pytest.fail("Message should not have been forwarded after transform error")
     finally:
         # Clean up test streams