fix(server): return 404 when deleting non-existent server (#1592)

* fix(server): ensure server exists before deletion in delete_server function

Signed-off-by: Duarte Martinho <dmartinho@ibm.com>

* test(server): update delete_server tests for existence check

Update test_delete_server_endpoint to mock get_server which is now
called before delete_server to verify server existence.

Add test_delete_server_not_found to verify that attempting to delete
a non-existent server returns HTTP 404 instead of 400.

Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>

---------

Signed-off-by: Duarte Martinho <dmartinho@ibm.com>
Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>
Co-authored-by: Duarte Martinho <dmartinho@ibm.com>

Author: crivetimihai

mcpgateway/main.py

@@ -1966,6 +1966,7 @@ async def delete_server(server_id: str, db: Session = Depends(get_db), user=Depe
     try:
         logger.debug(f"User {user} is deleting server with ID {server_id}")
         user_email = user.get("email") if isinstance(user, dict) else str(user)
+        await server_service.get_server(db, server_id)
         await server_service.delete_server(db, server_id, user_email=user_email)
         return {
             "status": "success",

tests/unit/mcpgateway/test_main.py

@@ -520,13 +520,25 @@ def test_toggle_server_status(self, mock_toggle, test_client, auth_headers):
         mock_toggle.assert_called_once()
 
     @patch("mcpgateway.main.server_service.delete_server")
-    def test_delete_server_endpoint(self, mock_delete, test_client, auth_headers):
+    @patch("mcpgateway.main.server_service.get_server")
+    def test_delete_server_endpoint(self, mock_get, mock_delete, test_client, auth_headers):
         """Test permanently deleting a server."""
+        mock_get.return_value = ServerRead(**MOCK_SERVER_READ)
         mock_delete.return_value = None
         response = test_client.delete("/servers/1", headers=auth_headers)
         assert response.status_code == 200
         assert response.json()["status"] == "success"
 
+    @patch("mcpgateway.main.server_service.get_server")
+    def test_delete_server_not_found(self, mock_get, test_client, auth_headers):
+        """Test deleting a non-existent server returns 404."""
+        from mcpgateway.services.server_service import ServerNotFoundError
+
+        mock_get.side_effect = ServerNotFoundError("Server not found: nonexistent-id")
+        response = test_client.delete("/servers/nonexistent-id", headers=auth_headers)
+        assert response.status_code == 404
+        assert "Server not found" in response.json()["detail"]
+
     @patch("mcpgateway.main.tool_service.list_server_tools")
     def test_server_get_tools(self, mock_list_tools, test_client, auth_headers):
         """Test listing tools associated with a server."""