TST: fix failures in expand_dims test

Author: crusaderky

tests/test_funcs.py

@@ -1,4 +1,3 @@
-import contextlib
 import math
 import warnings
 from types import ModuleType
@@ -24,7 +23,7 @@
 from array_api_extra._lib._testing import xp_assert_close, xp_assert_equal
 from array_api_extra._lib._utils._compat import device as get_device
 from array_api_extra._lib._utils._helpers import eager_shape, ndindex
-from array_api_extra._lib._utils._typing import Array, Device
+from array_api_extra._lib._utils._typing import Device
 from array_api_extra.testing import lazy_xp_function
 
 # some xp backends are untyped
@@ -291,22 +290,12 @@ def test_xp(self, xp: ModuleType):
 
 class TestExpandDims:
     @pytest.mark.xfail_xp_backend(Backend.SPARSE, reason="no expand_dims")
-    @pytest.mark.xfail_xp_backend(Backend.DASK, reason="tuple index out of range")
-    @pytest.mark.xfail_xp_backend(Backend.TORCH, reason="tuple index out of range")
-    def test_functionality(self, xp: ModuleType):
-        def _squeeze_all(b: Array) -> Array:
-            """Mimics `np.squeeze(b)`. `xpx.squeeze`?"""
-            for axis in range(b.ndim):
-                with contextlib.suppress(ValueError):
-                    b = xp.squeeze(b, axis=axis)
-            return b
-
-        s = (2, 3, 4, 5)
-        a = xp.empty(s)
+    def test_single_axis(self, xp: ModuleType):
+        """Trivial case where xpx.expand_dims doesn't add anything to xp.expand_dims"""
+        a = xp.empty((2, 3, 4, 5))
         for axis in range(-5, 4):
             b = expand_dims(a, axis=axis)
-            assert b.shape[axis] == 1
-            assert _squeeze_all(b).shape == s
+            xp_assert_equal(b, xp.expand_dims(a, axis=axis))
 
     @pytest.mark.xfail_xp_backend(Backend.SPARSE, reason="no expand_dims")
     def test_axis_tuple(self, xp: ModuleType):
@@ -317,8 +306,7 @@ def test_axis_tuple(self, xp: ModuleType):
         assert expand_dims(a, axis=(0, -3, -5)).shape == (1, 1, 3, 1, 3, 3)
 
     def test_axis_out_of_range(self, xp: ModuleType):
-        s = (2, 3, 4, 5)
-        a = xp.empty(s)
+        a = xp.empty((2, 3, 4, 5))
         with pytest.raises(IndexError, match="out of bounds"):
             _ = expand_dims(a, axis=-6)
         with pytest.raises(IndexError, match="out of bounds"):