diff --git a/idom/testing.py b/idom/testing.py
index cdac91fa7..0e24f3531 100644
--- a/idom/testing.py
+++ b/idom/testing.py
@@ -106,7 +106,7 @@ def open_mount_function(self) -> Iterator[_Mount]:
             yield self._mount
         finally:
             if self.server.last_server_error_for_idom_testing.current is not None:
-                raise self.server.last_server_error_for_idom_testing.current
+                raise self.server.last_server_error_for_idom_testing.current  # pragma: no cover
 
 
 class _RenderServerWithLastError(AnyRenderServer):