MAINT: refactor array API testing

doc/source/dev/api-dev/array_api.rst

@@ -238,20 +238,18 @@ The following pytest markers are available:
 
 The following is an example using the markers::
 
-  from scipy.conftest import array_api_compatible
+  from scipy._lib._array_api import array_api_compatible, skip_xp_backends
   ...
-  @pytest.mark.skip_xp_backends(np_only=True,
-                                 reasons=['skip reason'])
+  @skip_xp_backends(np_only=True, reasons=['skip reason'])
   @pytest.mark.usefixtures("skip_xp_backends")
   @array_api_compatible
   def test_toto1(self, xp):
       a = xp.asarray([1, 2, 3])
       b = xp.asarray([0, 2, 5])
       toto(a, b)
   ...
-  @pytest.mark.skip_xp_backends('array_api_strict', 'cupy',
-                                 reasons=['skip reason 1',
-                                          'skip reason 2',])
+  @skip_xp_backends('array_api_strict', 'cupy',
+                    reasons=['skip reason 1', 'skip reason 2',])
   @pytest.mark.usefixtures("skip_xp_backends")
   @array_api_compatible
   def test_toto2(self, xp):
@@ -268,10 +266,9 @@ When every test function in a file has been updated for array API
 compatibility, one can reduce verbosity by telling ``pytest`` to apply the
 markers to every test function using ``pytestmark``::
 
-    from scipy.conftest import array_api_compatible
+    from scipy._lib._array_api import array_api_compatible, skip_xp_backends
 
     pytestmark = [array_api_compatible, pytest.mark.usefixtures("skip_xp_backends")]
-    skip_xp_backends = pytest.mark.skip_xp_backends
     ...
     @skip_xp_backends(np_only=True, reasons=['skip reason'])
     def test_toto1(self, xp):

scipy/_lib/_array_api.py

@@ -20,13 +20,44 @@
     numpy as np_compat,
 )
 
-__all__ = ['array_namespace', '_asarray', 'size']
-
-
-# To enable array API and strict array-like input validation
-SCIPY_ARRAY_API: str | bool = os.environ.get("SCIPY_ARRAY_API", False)
-# To control the default device - for use in the test suite only
-SCIPY_DEVICE = os.environ.get("SCIPY_DEVICE", "cpu")
+try:
+    # try to get the experimental variables and pytest marks from conftest,
+    # will error if pytest is not installed.
+    import pytest
+    from scipy.conftest import (
+        array_api_compatible, SCIPY_ARRAY_API, SCIPY_DEVICE
+    )
+
+    skip_xp_backends = pytest.mark.skip_xp_backends
+except ImportError:
+    # define the experimental variables here instead
+
+    # To enable array API and strict array-like input validation
+    SCIPY_ARRAY_API: str | bool = os.environ.get("SCIPY_ARRAY_API", False)  # type: ignore[no-redef]  # noqa: E501
+    # To control the default device - for use in the test suite only
+    SCIPY_DEVICE = os.environ.get("SCIPY_DEVICE", "cpu")
+
+__all__ = [
+    '_GLOBAL_CONFIG',
+    'array_api_compatible',
+    'array_namespace',
+    '_asarray',
+    'atleast_nd',
+    'copy',
+    'cov',
+    'is_complex',
+    'is_cupy',
+    'is_numpy',
+    'is_torch',
+    'SCIPY_ARRAY_API',
+    'SCIPY_DEVICE',
+    'size',
+    'skip_xp_backends',
+    'xp_assert_close',
+    'xp_assert_equal',
+    'xp_assert_less',
+    'xp_unsupported_param_msg'
+]
 
 _GLOBAL_CONFIG = {
     "SCIPY_ARRAY_API": SCIPY_ARRAY_API,

scipy/_lib/tests/test__util.py

@@ -9,15 +9,15 @@
 import pytest
 from pytest import raises as assert_raises
 import hypothesis.extra.numpy as npst
-from hypothesis import given, strategies, reproduce_failure  # noqa: F401
-from scipy.conftest import array_api_compatible
+from hypothesis import given, strategies  # noqa: F401
 
-from scipy._lib._array_api import xp_assert_equal
 from scipy._lib._util import (_aligned_zeros, check_random_state, MapWrapper,
                               getfullargspec_no_self, FullArgSpec,
                               rng_integers, _validate_int, _rename_parameter,
                               _contains_nan, _rng_html_rewrite, _lazywhere)
 
+from scipy._lib._array_api import array_api_compatible, xp_assert_equal
+
 
 def test__aligned_zeros():
     niter = 10

scipy/_lib/tests/test_array_api.py

@@ -1,18 +1,24 @@
 import numpy as np
 import pytest
 
-from scipy.conftest import array_api_compatible
 from scipy._lib._array_api import (
-    _GLOBAL_CONFIG, array_namespace, _asarray, copy, xp_assert_equal, is_numpy
+    _GLOBAL_CONFIG,
+    array_api_compatible,
+    array_namespace,
+    _asarray,
+    copy,
+    is_numpy,
+    xp_assert_equal, 
 )
 import scipy._lib.array_api_compat.numpy as np_compat
 
 
+@array_api_compatible
 @pytest.mark.skipif(not _GLOBAL_CONFIG["SCIPY_ARRAY_API"],
         reason="Array API test; set environment variable SCIPY_ARRAY_API=1 to run it")
 class TestArrayAPI:
 
-    def test_array_namespace(self):
+    def test_array_namespace(self, xp):
         x, y = np.array([0, 1, 2]), np.array([0, 1, 2])
         xp = array_namespace(x, y)
         assert 'array_api_compat.numpy' in xp.__name__
@@ -22,15 +28,14 @@ def test_array_namespace(self):
         assert 'array_api_compat.numpy' in xp.__name__
         _GLOBAL_CONFIG["SCIPY_ARRAY_API"] = True
 
-    @array_api_compatible
     def test_asarray(self, xp):
         x, y = _asarray([0, 1, 2], xp=xp), _asarray(np.arange(3), xp=xp)
         ref = xp.asarray([0, 1, 2])
         xp_assert_equal(x, ref)
         xp_assert_equal(y, ref)
 
     @pytest.mark.filterwarnings("ignore: the matrix subclass")
-    def test_raises(self):
+    def test_raises(self, xp):
         msg = "of type `numpy.ma.MaskedArray` are not supported"
         with pytest.raises(TypeError, match=msg):
             array_namespace(np.ma.array(1), np.array(1))
@@ -45,13 +50,12 @@ def test_raises(self):
         with pytest.raises(TypeError, match=msg):
             array_namespace('abc')
 
-    def test_array_likes(self):
+    def test_array_likes(self, xp):
         # should be no exceptions
         array_namespace([0, 1, 2])
         array_namespace(1, 2, 3)
         array_namespace(1)
 
-    @array_api_compatible
     def test_copy(self, xp):
         for _xp in [xp, None]:
             x = xp.asarray([1, 2, 3])
@@ -67,7 +71,6 @@ def test_copy(self, xp):
             assert x[2] != y[2]
             assert id(x) != id(y)
 
-    @array_api_compatible
     @pytest.mark.parametrize('dtype', ['int32', 'int64', 'float32', 'float64'])
     @pytest.mark.parametrize('shape', [(), (3,)])
     def test_strict_checks(self, xp, dtype, shape):
@@ -98,7 +101,6 @@ def test_strict_checks(self, xp, dtype, shape):
             with pytest.raises(AssertionError, match="Shapes do not match."):
                 xp_assert_equal(x, y, **options)
 
-    @array_api_compatible
     def test_check_scalar(self, xp):
         if not is_numpy(xp):
             pytest.skip("Scalars only exist in NumPy")

scipy/cluster/tests/test_hierarchy.py

@@ -47,11 +47,11 @@
     _order_cluster_tree, _hierarchy, _LINKAGE_METHODS)
 from scipy.spatial.distance import pdist
 from scipy.cluster._hierarchy import Heap
-from scipy.conftest import array_api_compatible
-from scipy._lib._array_api import xp_assert_close, xp_assert_equal
-
 from . import hierarchy_test_data
 
+from scipy._lib._array_api import (
+    array_api_compatible, skip_xp_backends, xp_assert_close, xp_assert_equal,
+)
 
 # Matplotlib is not a scipy dependency but is optionally used in dendrogram, so
 # check if it's available
@@ -65,9 +65,7 @@
 except Exception:
     have_matplotlib = False
 
-
 pytestmark = [array_api_compatible, pytest.mark.usefixtures("skip_xp_backends")]
-skip_xp_backends = pytest.mark.skip_xp_backends
 
 
 class TestLinkage:

scipy/cluster/tests/test_vq.py

@@ -12,15 +12,19 @@
 from scipy.cluster.vq import (kmeans, kmeans2, py_vq, vq, whiten,
                               ClusterError, _krandinit)
 from scipy.cluster import _vq
-from scipy.conftest import array_api_compatible
 from scipy.sparse._sputils import matrix
 
 from scipy._lib._array_api import (
-    SCIPY_ARRAY_API, copy, cov, xp_assert_close, xp_assert_equal
+    array_api_compatible,
+    copy,
+    cov,
+    SCIPY_ARRAY_API,
+    skip_xp_backends,
+    xp_assert_close,
+    xp_assert_equal,
 )
 
 pytestmark = [array_api_compatible, pytest.mark.usefixtures("skip_xp_backends")]
-skip_xp_backends = pytest.mark.skip_xp_backends
 
 TESTDATA_2D = np.array([
     -2.2, 1.17, -1.63, 1.69, -2.04, 4.38, -3.09, 0.95, -1.7, 4.79, -1.68, 0.68,

scipy/cluster/vq.py

@@ -67,14 +67,15 @@
 import warnings
 import numpy as np
 from collections import deque
-from scipy._lib._array_api import (
-    _asarray, array_namespace, size, atleast_nd, copy, cov
-)
+
 from scipy._lib._util import check_random_state, rng_integers
 from scipy.spatial.distance import cdist
-
 from . import _vq
 
+from scipy._lib._array_api import (
+    _asarray, array_namespace, atleast_nd, copy, cov, size,
+)
+
 __docformat__ = 'restructuredtext'
 
 __all__ = ['whiten', 'vq', 'kmeans', 'kmeans2']

scipy/conftest.py

@@ -1,4 +1,5 @@
 # Pytest customization
+from __future__ import annotations
 import json
 import os
 import warnings
@@ -12,7 +13,6 @@
 from scipy._lib._fpumode import get_fpu_mode
 from scipy._lib._testutils import FPUModeChangeWarning
 from scipy._lib import _pep440
-from scipy._lib._array_api import SCIPY_ARRAY_API, SCIPY_DEVICE
 
 
 def pytest_configure(config):
@@ -107,6 +107,11 @@ def check_fpu_mode(request):
 # Array API backend handling
 xp_available_backends = {'numpy': np}
 
+# To enable array API and strict array-like input validation
+SCIPY_ARRAY_API: str | bool = os.environ.get("SCIPY_ARRAY_API", False)
+# To control the default device - for use in the test suite only
+SCIPY_DEVICE = os.environ.get("SCIPY_DEVICE", "cpu")
+
 if SCIPY_ARRAY_API and isinstance(SCIPY_ARRAY_API, str):
     # fill the dict of backends with available libraries
     try:

scipy/fft/_basic_backend.py

@@ -1,8 +1,9 @@
+import numpy as np
+from . import _pocketfft
+
 from scipy._lib._array_api import (
-    array_namespace, is_numpy, xp_unsupported_param_msg, is_complex
+    array_namespace, is_complex, is_numpy, xp_unsupported_param_msg,
 )
-from . import _pocketfft
-import numpy as np
 
 
 def _validate_fft_args(workers, plan, norm):

scipy/fft/_helper.py

@@ -1,9 +1,9 @@
 from functools import update_wrapper, lru_cache
 import inspect
 
+import numpy as np
 from ._pocketfft import helper as _helper
 
-import numpy as np
 from scipy._lib._array_api import array_namespace
 
 

scipy/fft/_realtransforms_backend.py

@@ -1,7 +1,8 @@
-from scipy._lib._array_api import array_namespace
 import numpy as np
 from . import _pocketfft
 
+from scipy._lib._array_api import array_namespace
+
 __all__ = ['dct', 'idct', 'dst', 'idst', 'dctn', 'idctn', 'dstn', 'idstn']
 
 

scipy/fft/tests/test_basic.py

@@ -6,14 +6,19 @@
 from numpy.random import random
 from numpy.testing import assert_array_almost_equal, assert_allclose
 from pytest import raises as assert_raises
+
 import scipy.fft as fft
-from scipy.conftest import array_api_compatible
+
 from scipy._lib._array_api import (
-    array_namespace, size, xp_assert_close, xp_assert_equal
+    array_api_compatible,
+    array_namespace,
+    size,
+    skip_xp_backends,
+    xp_assert_close,
+    xp_assert_equal,
 )
 
 pytestmark = [array_api_compatible, pytest.mark.usefixtures("skip_xp_backends")]
-skip_xp_backends = pytest.mark.skip_xp_backends
 
 
 # Expected input dtypes. Note that `scipy.fft` is more flexible for numpy,

scipy/fft/tests/test_fftlog.py

@@ -5,8 +5,7 @@
 from scipy.fft._fftlog import fht, ifht, fhtoffset
 from scipy.special import poch
 
-from scipy.conftest import array_api_compatible
-from scipy._lib._array_api import xp_assert_close
+from scipy._lib._array_api import array_api_compatible, xp_assert_close
 
 pytestmark = array_api_compatible
 

scipy/fft/tests/test_helper.py

@@ -4,18 +4,21 @@
 Modified for Array API, 2023
 
 """
-from scipy.fft._helper import next_fast_len, _init_nd_shape_and_axes
+
 from numpy.testing import assert_equal
 from pytest import raises as assert_raises
 import pytest
 import numpy as np
 import sys
-from scipy.conftest import array_api_compatible
-from scipy._lib._array_api import xp_assert_close, SCIPY_DEVICE
+
 from scipy import fft
+from scipy.fft._helper import next_fast_len, _init_nd_shape_and_axes
+
+from scipy._lib._array_api import (
+    array_api_compatible, SCIPY_DEVICE, skip_xp_backends, xp_assert_close,
+)
 
 pytestmark = [array_api_compatible, pytest.mark.usefixtures("skip_xp_backends")]
-skip_xp_backends = pytest.mark.skip_xp_backends
 
 _5_smooth_numbers = [
     2, 3, 4, 5, 6, 8, 9, 10,
@@ -24,6 +27,7 @@
     2**3 * 3**3 * 5**2,
 ]
 
+
 def test_next_fast_len():
     for n in _5_smooth_numbers:
         assert_equal(next_fast_len(n), n)

scipy/fft/tests/test_real_transforms.py

@@ -6,11 +6,12 @@
 from scipy.fft import dct, idct, dctn, idctn, dst, idst, dstn, idstn
 import scipy.fft as fft
 from scipy import fftpack
-from scipy.conftest import array_api_compatible
-from scipy._lib._array_api import copy, xp_assert_close
+
+from scipy._lib._array_api import (
+    array_api_compatible, copy, skip_xp_backends, xp_assert_close,
+)
 
 pytestmark = [array_api_compatible, pytest.mark.usefixtures("skip_xp_backends")]
-skip_xp_backends = pytest.mark.skip_xp_backends
 
 SQRT_2 = math.sqrt(2)