BUG: do not allow asarray of nested sequences of arrays

Author: ev-br

array_api_strict/_creation_functions.py

@@ -121,6 +121,10 @@ def asarray(
 
     if isinstance(obj, Array):
         return Array._new(np.array(obj._array, copy=copy, dtype=_np_dtype), device=device)
+    elif isinstance(obj, list | tuple):
+        if any(isinstance(x, Array) for x in obj):
+            raise TypeError("Nested Arrays are not allowed. Use `stack` instead.")
+
     if dtype is None and isinstance(obj, int) and (obj > 2 ** 64 or obj < -(2 ** 63)):
         # Give a better error message in this case. NumPy would convert this
         # to an object array. TODO: This won't handle large integers in lists.

array_api_strict/tests/test_creation_functions.py

@@ -97,18 +97,20 @@ def test_asarray_copy():
     a[0] = 0
     assert all(b[0] == 0)
 
+
 def test_asarray_list_of_lists():
-    a = asarray(1, dtype=int16)
-    b = asarray([1], dtype=int16)
-    res = asarray([a, a])
-    assert res.shape == (2,)
-    assert res.dtype == int16
-    assert all(res == asarray([1, 1]))
-
-    res = asarray([b, b])
-    assert res.shape == (2, 1)
-    assert res.dtype == int16
-    assert all(res == asarray([[1], [1]]))
+    lst = [[1, 2, 3], [4, 5, 6]]
+    res = asarray(lst)
+    assert res.shape == (2, 3)
+
+
+def test_asarray_nested_arrays():
+    # do not allow arrays in nested sequences
+    with pytest.raises(TypeError):
+        asarray([[1, 2, 3], asarray([4, 5, 6])])
+
+    with pytest.raises(TypeError):
+        asarray([1, asarray(1)])
 
 
 def test_asarray_device_inference():