def METHOD_NAME(tmp_path, file_format):
    a = AnnData(
        X=np.ones((5, 1)),
        obs=pd.DataFrame(
            {
                "cat_ordered": pd.Categorical(list("aabcd"), ordered=True),
            },
            index=[f"cell{i:02}" for i in range(5)],
        ),
    )
    b = AnnData(
        X=np.ones((5, 1)),
        obs=pd.DataFrame(
            {
                "cat_ordered": pd.Categorical(list("abcdd"), ordered=True),
            },
            index=[f"cell{i:02}" for i in range(5, 10)],
        ),
    )
    adatas = [a, b]
    assert_eq_concat_on_disk(adatas, tmp_path, file_format)