(fix): check xarray installation when using any xarray-dependent code + fix string dtypes with new bound

hatch.toml

@@ -15,7 +15,7 @@ scripts.clean = "git restore --source=HEAD --staged --worktree -- docs/release-n
 
 [envs.hatch-test]
 default-args = [  ]
-features = [ "dev", "test-min" ]
+features = [ "test-min" ]
 extra-dependencies = [ "ipykernel" ]
 env-vars.UV_CONSTRAINT = "ci/constraints.txt"
 overrides.matrix.deps.env-vars = [

src/anndata/_core/xarray.py

@@ -1,12 +1,26 @@
 from __future__ import annotations
 
 import warnings
+from functools import wraps
 
 import pandas as pd
 
 from ..compat import XDataArray, XDataset, XVariable
 
 
+def requires_xarray(func):
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        try:
+            import xarray  # noqa: F401
+        except ImportError as e:
+            msg = "xarray is required to read dataframes lazily. Please install xarray."
+            raise ImportError(msg) from e
+        return func(*args, **kwargs)
+
+    return wrapper
+
+
 class Dataset2D(XDataset):
     """
     A wrapper class meant to enable working with lazy dataframe data.

src/anndata/_io/specs/lazy_methods.py

@@ -12,7 +12,7 @@
 
 import anndata as ad
 from anndata._core.file_backing import filename, get_elem_name
-from anndata._core.xarray import Dataset2D
+from anndata._core.xarray import Dataset2D, requires_xarray
 from anndata.abc import CSCDataset, CSRDataset
 from anndata.compat import DaskArray, H5Array, H5Group, XDataArray, ZarrArray, ZarrGroup
 
@@ -258,6 +258,7 @@ def _gen_xarray_dict_iterator_from_elems(
 
 @_LAZY_REGISTRY.register_read(ZarrGroup, IOSpec("dataframe", "0.2.0"))
 @_LAZY_REGISTRY.register_read(H5Group, IOSpec("dataframe", "0.2.0"))
+@requires_xarray
 def read_dataframe(
     elem: H5Group | ZarrGroup,
     *,
@@ -297,6 +298,7 @@ def read_dataframe(
 
 @_LAZY_REGISTRY.register_read(ZarrGroup, IOSpec("categorical", "0.2.0"))
 @_LAZY_REGISTRY.register_read(H5Group, IOSpec("categorical", "0.2.0"))
+@requires_xarray
 def read_categorical(
     elem: H5Group | ZarrGroup,
     *,
@@ -317,6 +319,7 @@ def read_categorical(
     )
 
 
+@requires_xarray
 def read_nullable(
     elem: H5Group | ZarrGroup,
     *,

src/anndata/experimental/backed/_io.py

@@ -13,6 +13,7 @@
 from testing.anndata._doctest import doctest_needs
 
 from ..._core.anndata import AnnData
+from ..._core.xarray import requires_xarray
 from ..._settings import settings
 from ...compat import ZarrGroup, is_zarr_v2
 from .. import read_dispatched
@@ -25,6 +26,7 @@
 
 
 @doctest_needs("xarray")
+@requires_xarray
 def read_lazy(
     store: PathLike[str] | str | MutableMapping | ZarrGroup | h5py.Dataset,
     *,
@@ -81,13 +83,6 @@ def read_lazy(
     AnnData object with n_obs × n_vars = 490 × 33452
         obs: 'donor_id', 'self_reported_ethnicity_ontology_term_id', 'organism_ontology_term_id'...
     """
-    try:
-        import xarray  # noqa: F401
-    except ImportError as e:
-        msg = (
-            "xarray is required to use the `read_lazy` function. Please install xarray."
-        )
-        raise ImportError(msg) from e
     is_h5_store = isinstance(store, h5py.Dataset | h5py.File | h5py.Group)
     is_h5 = (
         isinstance(store, PathLike | str) and Path(store).suffix == ".h5ad"

tests/test_readwrite.py

@@ -952,8 +952,17 @@ def test_forward_slash_key(elem_key, tmp_path):
 
 
 @pytest.mark.skipif(
-    find_spec("xarray"), reason="Xarray is installed so `read_lazy` will not error"
+    find_spec("xarray"),
+    reason="Xarray is installed so `read_{elem_}lazy` will not error",
 )
-def test_read_lazy_import_error():
+@pytest.mark.parametrize(
+    "func", [ad.experimental.read_lazy, ad.experimental.read_elem_lazy]
+)
+def test_read_lazy_import_error(func, tmp_path):
+    ad.AnnData(np.ones((10, 10))).write_zarr(tmp_path)
     with pytest.raises(ImportError, match="xarray"):
-        ad.experimental.read_lazy("test.zarr")
+        func(
+            zarr.open(
+                tmp_path if func is ad.experimental.read_lazy else tmp_path / "obs"
+            )
+        )

tests/test_xarray.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import string
+from importlib.util import find_spec
 
 import numpy as np
 import pandas as pd
@@ -10,6 +11,8 @@
 from anndata.compat import XDataArray, XDataset, XVariable
 from anndata.tests.helpers import gen_typed_df
 
+pytestmark = pytest.mark.skipif(not find_spec("xarray"), reason="xarray not installed")
+
 
 @pytest.fixture
 def df():