fix: Replace arbitrary sleeps with active server readiness checks in tests (#1527)

Co-authored-by: Claude <noreply@anthropic.com>

tests/server/test_sse_security.py

@@ -3,7 +3,6 @@
 import logging
 import multiprocessing
 import socket
-import time
 
 import httpx
 import pytest
@@ -17,6 +16,7 @@ from mcp.server import Server
 from mcp.server.sse import SseServerTransport
 from mcp.server.transport_security import TransportSecuritySettings
 from mcp.types import Tool
+from tests.test_helpers import wait_for_server
 
 logger = logging.getLogger(__name__)
 SERVER_NAME = "test_sse_security_server"
@@ -66,26 +66,6 @@ def run_server_with_settings(port: int, security_settings: TransportSecuritySett
     uvicorn.run(starlette_app, host="127.0.0.1", port=port, log_level="error")
 
 
-def wait_for_server(port: int, timeout: float = 5.0) -> None:
-    """Wait for server to be ready to accept connections.
-
-    Polls the server port until it accepts connections or timeout is reached.
-    This eliminates race conditions without arbitrary sleeps.
-    """
-    start_time = time.time()
-    while time.time() - start_time < timeout:
-        try:
-            with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
-                s.settimeout(0.1)
-                s.connect(("127.0.0.1", port))
-                # Server is ready
-                return
-        except (ConnectionRefusedError, OSError):
-            # Server not ready yet, retry quickly
-            time.sleep(0.01)
-    raise TimeoutError(f"Server on port {port} did not start within {timeout} seconds")
-
-
 def start_server_process(port: int, security_settings: TransportSecuritySettings | None = None):
     """Start server in a separate process."""
     process = multiprocessing.Process(target=run_server_with_settings, args=(port, security_settings))

tests/server/test_streamable_http_security.py

@@ -3,7 +3,6 @@
 import logging
 import multiprocessing
 import socket
-import time
 from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
 
@@ -18,6 +17,7 @@ from mcp.server import Server
 from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
 from mcp.server.transport_security import TransportSecuritySettings
 from mcp.types import Tool
+from tests.test_helpers import wait_for_server
 
 logger = logging.getLogger(__name__)
 SERVER_NAME = "test_streamable_http_security_server"
@@ -77,8 +77,8 @@ def start_server_process(port: int, security_settings: TransportSecuritySettings
     """Start server in a separate process."""
     process = multiprocessing.Process(target=run_server_with_settings, args=(port, security_settings))
     process.start()
-    # Give server time to start
-    time.sleep(1)
+    # Wait for server to be ready to accept connections
+    wait_for_server(port)
     return process