fix: dak.copy should copy metadata

src/dask_awkward/lib/structure.py

@@ -3,6 +3,7 @@
 import builtins
 import warnings
 from collections.abc import Iterable, Mapping, Sequence
+from copy import deepcopy
 from numbers import Number
 from typing import TYPE_CHECKING, Any
 
@@ -315,7 +316,17 @@ def combinations(
 
 @borrow_docstring(ak.copy)
 def copy(array: Array) -> Array:
- return array
+ # Make a copy of meta, but don't try and copy the layout;
+ # dask-awkward's copy is metadata-only
+ old_meta = array._meta
+ new_meta = ak.Array(old_meta.layout, behavior=deepcopy(old_meta._behavior))
+
+ return Array(
+ array._dask,
+ array._name,
+ new_meta,
+ array._divisions,
+ )
 
 
 class _FillNoneFn:

tests/test_structure.py

@@ -388,11 +388,8 @@ def test_sort(daa, caa, ascending):
 
 
 def test_copy(daa):
- with pytest.raises(
- DaskAwkwardNotImplemented,
- match="This function is not necessary in the context of dask-awkward.",
- ):
- dak.copy(daa)
+ result = dak.copy(daa)
+ assert result._meta is not daa._meta
 
 
 @pytest.mark.parametrize(