Make array_type a session-scoped fixture

src/testing/fast_array_utils/_array_type.py

@@ -77,7 +77,7 @@ class Flags(enum.Flag):
 class ConversionContext:
     """Conversion context required for h5py."""
 
-    hdf5_file: h5py.File
+    hdf5_file: h5py.File  # TODO(flying-sheep): ReadOnly <https://peps.python.org/pep-0767/>
 
 
 @dataclass(frozen=True)

src/testing/fast_array_utils/pytest.py

@@ -7,6 +7,8 @@
 from __future__ import annotations
 
 import dataclasses
+import os
+import re
 from importlib.util import find_spec
 from typing import TYPE_CHECKING, cast
 
@@ -93,8 +95,8 @@ def _skip_if_unimportable(array_type: ArrayType) -> pytest.MarkDecorator:
 ]
 
 
-@pytest.fixture(params=SUPPORTED_TYPE_PARAMS)
-def array_type(request: pytest.FixtureRequest, tmp_path: Path) -> Generator[ArrayType, None, None]:
+@pytest.fixture(scope="session", params=SUPPORTED_TYPE_PARAMS)
+def array_type(request: pytest.FixtureRequest) -> ArrayType:
     """Fixture for a supported :class:`~testing.fast_array_utils.ArrayType`.
 
     Use :class:`testing.fast_array_utils.Flags` to select or skip array types:
@@ -131,13 +133,42 @@ def test_something(array_type: ArrayType) -> None:
             ...
     """
     at = cast("ArrayType", request.param)
-    f: h5py.File | None = None
     if at.cls is types.H5Dataset or (at.inner and at.inner.cls is types.H5Dataset):
+        at = dataclasses.replace(at, conversion_context=CC(request))
+    return at
+
+
+try:  # get the exception type
+    pytest.fail("x")
+except BaseException as e:  # noqa: BLE001
+    Failed = type(e)
+else:
+    raise AssertionError
+
+
+class CC(ConversionContext):
+    def __init__(self, request: pytest.FixtureRequest) -> None:
+        self._request = request
+
+    @property  # This is intentionally not cached and creates a new file on each access
+    def hdf5_file(self) -> h5py.File:  # type: ignore[override]
         import h5py
 
-        f = h5py.File(tmp_path / f"{request.fixturename}.h5", "w")
-        ctx = ConversionContext(hdf5_file=f)
-        at = dataclasses.replace(at, conversion_context=ctx)
-    yield at
-    if f:
-        f.close()
+        try:  # If we’re being called in a test or function-scoped fixture, use the test `tmp_path`
+            return cast("h5py.File", self._request.getfixturevalue("tmp_hdf5_file"))
+        except Failed:  # We’re being called from a session-scoped fixture or so
+            factory = cast(
+                "pytest.TempPathFactory", self._request.getfixturevalue("tmp_path_factory")
+            )
+            name = re.sub(r"[^\w_. -()\[\]{}]", "_", os.environ["PYTEST_CURRENT_TEST"])
+            f = h5py.File(factory.mktemp(name) / "test.h5", "w")
+            self._request.addfinalizer(f.close)
+            return f
+
+
+@pytest.fixture
+def tmp_hdf5_file(tmp_path: Path) -> Generator[h5py.File, None, None]:
+    import h5py
+
+    with h5py.File(tmp_path / "test.h5", "w") as f:
+        yield f

tests/test_test_utils.py

@@ -19,7 +19,7 @@
     from numpy.typing import DTypeLike, NDArray
     from scipy.sparse import coo_array, coo_matrix
 
-    from testing.fast_array_utils import ArrayType
+    from testing.fast_array_utils import Array, ArrayType
 
 
 other_array_type = array_type
@@ -78,3 +78,14 @@ def test_array_types(array_type: ArrayType) -> None:
     assert any(
         getattr(t, "mod", None) in {"zarr", "h5py"} for t in (array_type, array_type.inner)
     ) == bool(array_type.flags & Flags.Disk)
+
+
+@pytest.fixture(scope="session")
+def session_scoped_array(array_type: ArrayType) -> Array:
+    return array_type(np.arange(12).reshape(3, 4), dtype=np.float32)
+
+
+def test_session_scoped_array(session_scoped_array: Array) -> None:
+    """Tests that creating a session-scoped array works."""
+    assert session_scoped_array.shape == (3, 4)
+    assert session_scoped_array.dtype == np.float32

typings/h5py.pyi

@@ -17,6 +17,10 @@ class Dataset(HLObject):
 class Group(HLObject): ...
 
 class File(Group, closing[File]):  # not actually a subclass of closing
+    filename: str
+    mode: Literal["r", "r+"]
+    libver: Literal["earliest", "latest", "v108", "v110"]
+
     def __init__(
         self,
         name: AnyStr | os.PathLike[AnyStr] | IO[bytes],