Release resilient atomic Napseer CLI runtime

tests/test_mcp_supervisor.py

@@ -0,0 +1,116 @@
+import json
+import os
+import pathlib
+import select
+import signal
+import subprocess
+import sys
+import time
+
+
+ROOT = pathlib.Path(__file__).resolve().parents[1]
+SUPERVISOR = ROOT / "resources" / "scripts" / "napseer_mcp_supervisor.py"
+
+
+def write_worker(path: pathlib.Path, version: int) -> None:
+    path.write_text(
+        f"""\
+import json
+import os
+import sys
+
+VERSION = {version}
+
+for line in sys.stdin:
+    message = json.loads(line)
+    if message.get("method") == "notifications/initialized":
+        continue
+    if message.get("method") == "tools/call":
+        name = (message.get("params") or {{}}).get("name")
+        if name == "crash":
+            os._exit(17)
+        result = {{"pid": os.getpid(), "version": VERSION, "name": name}}
+    else:
+        result = {{"version": VERSION}}
+    print(json.dumps({{"jsonrpc": "2.0", "id": message.get("id"), "result": result}}), flush=True)
+""",
+        encoding="utf-8",
+    )
+
+
+class SupervisorClient:
+    def __init__(self, worker_path: pathlib.Path):
+        environment = os.environ.copy()
+        environment["NAPSEER_MCP_WORKER_PATH"] = str(worker_path)
+        environment["NAPSEER_MCP_RESPONSE_TIMEOUT_SECONDS"] = "5"
+        self.process = subprocess.Popen(
+            [sys.executable, str(SUPERVISOR)],
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            env=environment,
+        )
+
+    def request(self, request_id: int, method: str, params=None):
+        assert self.process.stdin is not None
+        assert self.process.stdout is not None
+        message = {"jsonrpc": "2.0", "id": request_id, "method": method}
+        if params is not None:
+            message["params"] = params
+        self.process.stdin.write(json.dumps(message).encode("utf-8") + b"\n")
+        self.process.stdin.flush()
+        readable, _, _ = select.select([self.process.stdout], [], [], 8)
+        assert readable, "supervisor did not return a response"
+        return json.loads(self.process.stdout.readline())
+
+    def close(self):
+        if self.process.poll() is None:
+            self.process.terminate()
+            self.process.wait(timeout=5)
+
+
+def test_restarts_worker_killed_between_requests(tmp_path):
+    worker_path = tmp_path / "worker.py"
+    write_worker(worker_path, 1)
+    client = SupervisorClient(worker_path)
+    try:
+        first = client.request(1, "tools/call", {"name": "pid", "arguments": {}})
+        os.kill(first["result"]["pid"], signal.SIGTERM)
+        time.sleep(0.1)
+
+        second = client.request(2, "tools/list")
+
+        assert second["result"]["version"] == 1
+        assert client.process.poll() is None
+    finally:
+        client.close()
+
+
+def test_reloads_replaced_worker_between_requests(tmp_path):
+    worker_path = tmp_path / "worker.py"
+    write_worker(worker_path, 1)
+    client = SupervisorClient(worker_path)
+    try:
+        assert client.request(1, "initialize")["result"]["version"] == 1
+        time.sleep(0.01)
+        write_worker(worker_path, 2)
+        os.utime(worker_path, None)
+
+        assert client.request(2, "tools/list")["result"]["version"] == 2
+    finally:
+        client.close()
+
+
+def test_worker_crash_returns_error_without_closing_transport(tmp_path):
+    worker_path = tmp_path / "worker.py"
+    write_worker(worker_path, 1)
+    client = SupervisorClient(worker_path)
+    try:
+        failed = client.request(1, "tools/call", {"name": "crash", "arguments": {}})
+        recovered = client.request(2, "tools/list")
+
+        assert failed["error"]["code"] == -32098
+        assert recovered["result"]["version"] == 1
+        assert client.process.poll() is None
+    finally:
+        client.close()