diff --git a/array_api_compat/dask/array/_aliases.py b/array_api_compat/dask/array/_aliases.py
index 9687a9cd..d43881ab 100644
--- a/array_api_compat/dask/array/_aliases.py
+++ b/array_api_compat/dask/array/_aliases.py
@@ -171,7 +171,7 @@ def asarray(
         return obj.copy() if copy else obj  # pyright: ignore[reportAttributeAccessIssue]
 
     if copy is False:
-        raise NotImplementedError(
+        raise ValueError(
             "Unable to avoid copy when converting a non-dask object to dask"
         )
 
diff --git a/tests/test_common.py b/tests/test_common.py
index d1933899..54b5ed69 100644
--- a/tests/test_common.py
+++ b/tests/test_common.py
@@ -268,7 +268,6 @@ def test_asarray_cross_library(source_library, target_library, request):
     assert b.dtype == tgt_lib.int32
 
 
-
 @pytest.mark.parametrize("library", wrapped_libraries)
 def test_asarray_copy(library):
     # Note, we have this test here because the test suite currently doesn't
@@ -278,100 +277,87 @@ def test_asarray_copy(library):
     xp = import_(library, wrapper=True)
     asarray = xp.asarray
     is_lib_func = globals()[is_array_functions[library]]
-    all = xp.all if library != 'dask.array' else lambda x: xp.all(x).compute()
-
-    if library == 'cupy':
-        supports_copy_false_other_ns = False
-        supports_copy_false_same_ns = False
-    elif library == 'dask.array':
-        supports_copy_false_other_ns = False
-        supports_copy_false_same_ns = True
-    else:
-        supports_copy_false_other_ns = True
-        supports_copy_false_same_ns = True
 
     a = asarray([1])
     b = asarray(a, copy=True)
     assert is_lib_func(b)
     a[0] = 0
-    assert all(b[0] == 1)
-    assert all(a[0] == 0)
+    assert b[0] == 1
+    assert a[0] == 0
 
     a = asarray([1])
-    if supports_copy_false_same_ns:
-        b = asarray(a, copy=False)
-        assert is_lib_func(b)
-        a[0] = 0
-        assert all(b[0] == 0)
-    else:
-        pytest.raises(NotImplementedError, lambda: asarray(a, copy=False))
 
-    a = asarray([1])
-    if supports_copy_false_same_ns:
-        pytest.raises(ValueError, lambda: asarray(a, copy=False,
-                                                  dtype=xp.float64))
-    else:
-        pytest.raises(NotImplementedError, lambda: asarray(a, copy=False, dtype=xp.float64))
+    # Test copy=False within the same namespace
+    b = asarray(a, copy=False)
+    assert is_lib_func(b)
+    a[0] = 0
+    assert b[0] == 0
+    with pytest.raises(ValueError):
+        asarray(a, copy=False, dtype=xp.float64)
 
+    # copy=None defaults to False when possible
     a = asarray([1])
     b = asarray(a, copy=None)
     assert is_lib_func(b)
     a[0] = 0
-    assert all(b[0] == 0)
+    assert b[0] == 0
 
+    # copy=None defaults to True when impossible
     a = asarray([1.0], dtype=xp.float32)
     assert a.dtype == xp.float32
     b = asarray(a, dtype=xp.float64, copy=None)
     assert is_lib_func(b)
     assert b.dtype == xp.float64
     a[0] = 0.0
-    assert all(b[0] == 1.0)
+    assert b[0] == 1.0
 
+    # copy=None defaults to False when possible
     a = asarray([1.0], dtype=xp.float64)
     assert a.dtype == xp.float64
     b = asarray(a, dtype=xp.float64, copy=None)
     assert is_lib_func(b)
     assert b.dtype == xp.float64
     a[0] = 0.0
-    assert all(b[0] == 0.0)
+    assert b[0] == 0.0
 
     # Python built-in types
     for obj in [True, 0, 0.0, 0j, [0], [[0]]]:
-        asarray(obj, copy=True) # No error
-        asarray(obj, copy=None) # No error
-        if supports_copy_false_other_ns:
-            pytest.raises(ValueError, lambda: asarray(obj, copy=False))
-        else:
-            pytest.raises(NotImplementedError, lambda: asarray(obj, copy=False))
+        asarray(obj, copy=True)  # No error
+        asarray(obj, copy=None)  # No error
+
+        with pytest.raises(ValueError):
+            asarray(obj, copy=False)
 
     # Use the standard library array to test the buffer protocol
-    a = array.array('f', [1.0])
+    a = array.array("f", [1.0])
     b = asarray(a, copy=True)
     assert is_lib_func(b)
     a[0] = 0.0
-    assert all(b[0] == 1.0)
+    assert b[0] == 1.0
 
-    a = array.array('f', [1.0])
-    if supports_copy_false_other_ns:
+    a = array.array("f", [1.0])
+    if library in ("cupy", "dask.array"):
+        with pytest.raises(ValueError):
+            asarray(a, copy=False)
+    else:
         b = asarray(a, copy=False)
         assert is_lib_func(b)
         a[0] = 0.0
-        assert all(b[0] == 0.0)
-    else:
-        pytest.raises(NotImplementedError, lambda: asarray(a, copy=False))
+        assert b[0] == 0.0
 
-    a = array.array('f', [1.0])
+    a = array.array("f", [1.0])
     b = asarray(a, copy=None)
     assert is_lib_func(b)
     a[0] = 0.0
-    if library in ('cupy', 'dask.array'):
+    if library in ("cupy", "dask.array"):
         # A copy is required for libraries where the default device is not CPU
         # dask changed behaviour of copy=None in 2024.12 to copy;
         # this wrapper ensures the same behaviour in older versions too.
         # https://github.com/dask/dask/pull/11524/
-        assert all(b[0] == 1.0)
+        assert b[0] == 1.0
     else:
-        assert all(b[0] == 0.0)
+        # copy=None defaults to False when possible
+        assert b[0] == 0.0
 
 
 @pytest.mark.parametrize("library", ["numpy", "cupy", "torch"])