Test get_previous_step_or_raise function
Currently, we do not test the function `get_previous_step_or_raise` (in `libcommon.simple_cache`).

We need to implement some tests of it, as discussed in: https://github.com/huggingface/datasets-server/pull/1418#discussion_r1240000135
Test get_previous_step_or_raise function: Currently, we do not test the function `get_previous_step_or_raise` (in `libcommon.simple_cache`).

We need to implement some tests of it, as discussed in: https://github.com/huggingface/datasets-server/pull/1418#discussion_r1240000135