From 8d9e897dcabd6569a778a97fc3446143d9ed1604 Mon Sep 17 00:00:00 2001
From: keewis <keewis@users.noreply.github.com>
Date: Fri, 26 Mar 2021 23:00:52 +0100
Subject: [PATCH] remove nep18 compatibility code (#5064)

---
 xarray/core/npcompat.py         | 15 ---------------
 xarray/core/variable.py         | 12 +-----------
 xarray/tests/test_dataset.py    |  2 --
 xarray/tests/test_formatting.py |  2 --
 xarray/tests/test_sparse.py     |  6 ------
 xarray/tests/test_testing.py    |  5 -----
 xarray/tests/test_units.py      |  4 ----
 7 files changed, 1 insertion(+), 45 deletions(-)

diff --git a/xarray/core/npcompat.py b/xarray/core/npcompat.py
index 4016fe44ca6..b319648886e 100644
--- a/xarray/core/npcompat.py
+++ b/xarray/core/npcompat.py
@@ -84,21 +84,6 @@ def moveaxis(a, source, destination):
     DTypeLike = Union[np.dtype, str]  # type: ignore
 
 
-# from dask/array/utils.py
-def _is_nep18_active():
-    class A:
-        def __array_function__(self, *args, **kwargs):
-            return True
-
-    try:
-        return np.concatenate([A()])
-    except ValueError:
-        return False
-
-
-IS_NEP18_ACTIVE = _is_nep18_active()
-
-
 if LooseVersion(np.__version__) >= "1.20.0":
     sliding_window_view = np.lib.stride_tricks.sliding_window_view
 else:
diff --git a/xarray/core/variable.py b/xarray/core/variable.py
index 272d7c355ea..2e97fad91b2 100644
--- a/xarray/core/variable.py
+++ b/xarray/core/variable.py
@@ -32,7 +32,6 @@
     VectorizedIndexer,
     as_indexable,
 )
-from .npcompat import IS_NEP18_ACTIVE
 from .options import _get_keep_attrs
 from .pycompat import (
     cupy_array_type,
@@ -242,16 +241,7 @@ def as_compatible_data(data, fastpath=False):
 
     if not isinstance(data, np.ndarray):
         if hasattr(data, "__array_function__"):
-            if IS_NEP18_ACTIVE:
-                return data
-            else:
-                raise TypeError(
-                    "Got an NumPy-like array type providing the "
-                    "__array_function__ protocol but NEP18 is not enabled. "
-                    "Check that numpy >= v1.16 and that the environment "
-                    'variable "NUMPY_EXPERIMENTAL_ARRAY_FUNCTION" is set to '
-                    '"1"'
-                )
+            return data
 
     # validate whether the data is valid data types.
     data = np.asarray(data)
diff --git a/xarray/tests/test_dataset.py b/xarray/tests/test_dataset.py
index 52df7603034..fb15f15df1a 100644
--- a/xarray/tests/test_dataset.py
+++ b/xarray/tests/test_dataset.py
@@ -28,7 +28,6 @@
 from xarray.coding.cftimeindex import CFTimeIndex
 from xarray.core import dtypes, indexing, utils
 from xarray.core.common import duck_array_ops, full_like
-from xarray.core.npcompat import IS_NEP18_ACTIVE
 from xarray.core.pycompat import integer_types
 from xarray.core.utils import is_scalar
 
@@ -320,7 +319,6 @@ def test_unicode_data(self):
         actual = str(data)
         assert expected == actual
 
-    @pytest.mark.skipif(not IS_NEP18_ACTIVE, reason="requires __array_function__")
     def test_repr_nep18(self):
         class Array:
             def __init__(self):
diff --git a/xarray/tests/test_formatting.py b/xarray/tests/test_formatting.py
index f2facf5b481..889e76cf99f 100644
--- a/xarray/tests/test_formatting.py
+++ b/xarray/tests/test_formatting.py
@@ -7,7 +7,6 @@
 
 import xarray as xr
 from xarray.core import formatting
-from xarray.core.npcompat import IS_NEP18_ACTIVE
 
 from . import raises_regex
 
@@ -395,7 +394,6 @@ def test_array_repr(self):
         assert actual == expected
 
 
-@pytest.mark.skipif(not IS_NEP18_ACTIVE, reason="requires __array_function__")
 def test_inline_variable_array_repr_custom_repr():
     class CustomArray:
         def __init__(self, value, attr):
diff --git a/xarray/tests/test_sparse.py b/xarray/tests/test_sparse.py
index 07d8df7a5a5..7ab5fbeb10a 100644
--- a/xarray/tests/test_sparse.py
+++ b/xarray/tests/test_sparse.py
@@ -8,7 +8,6 @@
 import xarray as xr
 import xarray.ufuncs as xu
 from xarray import DataArray, Variable
-from xarray.core.npcompat import IS_NEP18_ACTIVE
 from xarray.core.pycompat import sparse_array_type
 
 from . import assert_equal, assert_identical, requires_dask
@@ -16,11 +15,6 @@
 param = pytest.param
 xfail = pytest.mark.xfail
 
-if not IS_NEP18_ACTIVE:
-    pytest.skip(
-        "NUMPY_EXPERIMENTAL_ARRAY_FUNCTION is not enabled", allow_module_level=True
-    )
-
 sparse = pytest.importorskip("sparse")
 
 
diff --git a/xarray/tests/test_testing.py b/xarray/tests/test_testing.py
index b6dec846c54..7df7a45a04e 100644
--- a/xarray/tests/test_testing.py
+++ b/xarray/tests/test_testing.py
@@ -4,7 +4,6 @@
 import pytest
 
 import xarray as xr
-from xarray.core.npcompat import IS_NEP18_ACTIVE
 
 from . import has_dask
 
@@ -99,10 +98,6 @@ def test_assert_duckarray_equal_failing(duckarray, obj1, obj2):
         pytest.param(
             np.array,
             id="numpy",
-            marks=pytest.mark.skipif(
-                not IS_NEP18_ACTIVE,
-                reason="NUMPY_EXPERIMENTAL_ARRAY_FUNCTION is not enabled",
-            ),
         ),
         pytest.param(
             dask_from_array,
diff --git a/xarray/tests/test_units.py b/xarray/tests/test_units.py
index 8b7835e5da6..cc3c1a292ec 100644
--- a/xarray/tests/test_units.py
+++ b/xarray/tests/test_units.py
@@ -7,7 +7,6 @@
 
 import xarray as xr
 from xarray.core import dtypes
-from xarray.core.npcompat import IS_NEP18_ACTIVE
 
 from . import assert_allclose, assert_duckarray_allclose, assert_equal, assert_identical
 from .test_variable import _PAD_XR_NP_ARGS
@@ -23,9 +22,6 @@
 
 
 pytestmark = [
-    pytest.mark.skipif(
-        not IS_NEP18_ACTIVE, reason="NUMPY_EXPERIMENTAL_ARRAY_FUNCTION is not enabled"
-    ),
     pytest.mark.filterwarnings("error::pint.UnitStrippedWarning"),
 ]