TST: make xp_assert_{equal,close} scalar check opt-in #20959
Description
In [10]: from scipy._lib._array_api import xp_assert_close, xp_assert_equal
In [11]: a = np.array(42)
In [12]: xp_assert_equal(a, a)
---------------------------------------------------------------------------
AssertionError Traceback (most recent call last)
Cell In[12], line 1
----> 1 xp_assert_equal(a, a)
[... skipping hidden 2 frame]
File ~/repos/scipy/scipy/build-install/lib/python3.10/site-packages/scipy/_lib/_array_api.py:290, in _check_scalar(actual, desired, xp)
288 desired = desired[()]
289 _msg = f"Types do not match:\n Actual: {type(actual)}\n Desired: {type(desired)}"
--> 290 assert (xp.isscalar(actual) and xp.isscalar(desired)
291 or (not xp.isscalar(actual) and not xp.isscalar(desired))), _msg
AssertionError: Types do not match:
Actual: <class 'numpy.ndarray'>
Desired: <class 'numpy.int64'>
In [13]: xp_assert_close(a, a)
---------------------------------------------------------------------------
AssertionError Traceback (most recent call last)
Cell In[13], line 1
----> 1 xp_assert_close(a, a)
[... skipping hidden 2 frame]
File ~/repos/scipy/scipy/build-install/lib/python3.10/site-packages/scipy/_lib/_array_api.py:290, in _check_scalar(actual, desired, xp)
288 desired = desired[()]
289 _msg = f"Types do not match:\n Actual: {type(actual)}\n Desired: {type(desired)}"
--> 290 assert (xp.isscalar(actual) and xp.isscalar(desired)
291 or (not xp.isscalar(actual) and not xp.isscalar(desired))), _msg
AssertionError: Types do not match:
Actual: <class 'numpy.ndarray'>
Desired: <class 'numpy.int64'>