This test fails because instead of being `[1]` the node id is `[a-1]`. In other words the first `arg` fixture created seems to be in 'auto use' mode. ```python import pytest from pytest_cases import param_fixtures arg = param_fixtures('arg', ['a', 'b']) @pytest.mark.parametrize("arg", [1]) def test_reference2(arg, request): assert '[1]' in request.node.nodeid ``` Note that this does not happen with `param_fixture`.