Files
Skald-Circle/crates/mcp-client/tests/pagination.rs
T
2026-07-10 15:02:09 +01:00

104 lines
3.5 KiB
Rust

//! End-to-end test of `tools/list` cursor pagination against a real stdio MCP
//! subprocess.
//!
//! A tiny Python "server" returns its tools across two pages: the first
//! `tools/list` (no `cursor`) yields one tool plus a `nextCursor`; the follow-up
//! (with that `cursor`) yields the rest and no `nextCursor`. This exercises the
//! cursor loop in `McpServer::start`. Skipped if `python3` is absent.
use std::io::Write;
use std::process::Command;
use mcp_client::config::{McpServerConfig, McpTransport};
use mcp_client::server::McpServer;
const FAKE_SERVER: &str = r#"
import sys, json
def send(obj):
sys.stdout.write(json.dumps(obj) + "\n")
sys.stdout.flush()
def readline():
line = sys.stdin.readline()
if not line:
return None
line = line.strip()
return line if line else readline()
while True:
raw = readline()
if raw is None:
break
msg = json.loads(raw)
mid = msg.get("id")
method = msg.get("method")
if method == "initialize":
send({"jsonrpc": "2.0", "id": mid, "result": {
"protocolVersion": "2025-11-25", "capabilities": {},
"serverInfo": {"name": "fake", "version": "0"}}})
elif method == "notifications/initialized":
pass
elif method == "tools/list":
cursor = (msg.get("params") or {}).get("cursor")
if cursor is None:
# Page 1: one tool + a cursor pointing at the next page.
send({"jsonrpc": "2.0", "id": mid, "result": {
"tools": [{"name": "alpha", "description": "first",
"inputSchema": {"type": "object", "properties": {}}}],
"nextCursor": "page-2"}})
elif cursor == "page-2":
# Page 2: the rest, no further cursor → loop terminates.
send({"jsonrpc": "2.0", "id": mid, "result": {
"tools": [{"name": "beta", "description": "second",
"inputSchema": {"type": "object", "properties": {}}},
{"name": "gamma", "description": "third",
"inputSchema": {"type": "object", "properties": {}}}]}})
else:
send({"jsonrpc": "2.0", "id": mid, "result": {"tools": []}})
elif mid is not None:
send({"jsonrpc": "2.0", "id": mid, "error": {"code": -32601, "message": "unknown"}})
"#;
fn python3_available() -> bool {
Command::new("python3").arg("--version").output().is_ok()
}
#[tokio::test]
async fn tools_list_follows_next_cursor_across_pages() {
if !python3_available() {
eprintln!("python3 not found — skipping pagination integration test");
return;
}
let script_path =
std::env::temp_dir().join(format!("skald_paginate_{}.py", std::process::id()));
std::fs::File::create(&script_path)
.unwrap()
.write_all(FAKE_SERVER.as_bytes())
.unwrap();
let cfg = McpServerConfig {
name: "fake".to_string(),
transport: McpTransport::Stdio,
command: Some("python3".to_string()),
args: Some(vec![script_path.to_string_lossy().to_string()]),
env: None,
url: None,
api_key: None,
};
let server = McpServer::start(&cfg, None, None, None)
.await
.expect("server should start");
let names: Vec<&str> = server.tools().iter().map(|t| t.name.as_str()).collect();
assert_eq!(
names,
vec!["alpha", "beta", "gamma"],
"all pages should be collected"
);
let _ = std::fs::remove_file(&script_path);
}