add unit test for Streamable HTTP Trailing Slash Compatibility

Author: chiliu

tests/server/test_fastmcp_streamable_http_mount.py

@@ -1,7 +1,7 @@
 """Test FastMCP streamable_http_app mounts both /mcp and /mcp/ automatically."""
 
+import httpx
 import pytest
-from starlette.testclient import TestClient
 from mcp.server.fastmcp import FastMCP
 
 @pytest.fixture
@@ -11,11 +11,15 @@ def fastmcp_app():
     return app
 
 def test_streamable_http_mount_dual_paths(fastmcp_app):
-    client = TestClient(fastmcp_app)
+    # Use httpx.ASGITransport to avoid DeprecationWarning
+    transport = httpx.ASGITransport(app=fastmcp_app)
+    client = httpx.Client(transport=transport, base_url="http://testserver")
     for path in ["/mcp", "/mcp/"]:
         # Should return 406 because Accept header is missing, but proves route exists
-        resp = client.post(path, json={"jsonrpc": "2.0", "method": "initialize", "id": 1})
+        resp = client.post(
+            path, json={"jsonrpc": "2.0", "method": "initialize", "id": 1}
+        )
         assert resp.status_code in (400, 406)  # 406 Not Acceptable or 400 Bad Request
         # Optionally, test GET as well
         resp_get = client.get(path)
-        assert resp_get.status_code in (400, 406, 405)  # 405 if GET not allowed
+        assert resp_get.status_code in (400, 406, 405)