@pytest.mark.parametrize(
    "existing", ["x", "x/y"], ids=["unescaped-group", "escaped-group"]
)
@pytest.mark.parametrize("key", ["a/b", "100%"])
@pytest.mark.parametrize(
    "use", [lambda k: A.obsm[k], lambda _: A.obsm], ids=["single-key", "mapping"]
)
def test_use_escapes_keys(
    diskfmt_store: Path | MemoryStore,
    diskfmt: Literal["h5ad", "zarr"],
    existing: str,
    key: str,
    use: Callable[[str], object],
) -> None:
    """`use=` escapes keys like a full write with the same `compat` does.

    `100%` into an already escaped group is the silent case:
    written literally, it would be read back as an escape sequence.
    """
    adata = ad.AnnData(np.zeros((2, 3)), obsm={existing: np.zeros((2, 2))})
    getattr(adata, f"write_{diskfmt}")(diskfmt_store, compat="0.14")

    adata.obsm[key] = np.ones((2, 2))
    getattr(adata, f"write_{diskfmt}")(diskfmt_store, use=use(key), compat="0.14")
    back = getattr(ad, f"read_{diskfmt}")(diskfmt_store)

    assert set(back.obsm) == {existing, key}
    np.testing.assert_array_equal(back.obsm[key], np.ones((2, 2)))