SinglefileData: Fix bug when filename is pathlib.Path (#6006)

It would raise an exception when the node was stored since it would
compare the `filename` against the list of objects, but the latter would
be instances of a string instead of `pathlib.Path` and the validation
would fail. On top of that, the difference in type was not visible as
the cause in the error message, making for a cryptic error.

aiida/orm/nodes/data/singlefile.py

@@ -8,6 +8,8 @@
 # For further information please visit http://www.aiida.net               #
 ###########################################################################
 """Data class that can be used to store a single file in its repository."""
+from __future__ import annotations
+
 import contextlib
 import os
 import pathlib
@@ -24,7 +26,7 @@ class SinglefileData(Data):
 
     DEFAULT_FILENAME = 'file.txt'
 
-    def __init__(self, file, filename=None, **kwargs):
+    def __init__(self, file, filename: str | pathlib.Path | None = None, **kwargs):
         """Construct a new instance and set the contents to that of the file.
 
         :param file: an absolute filepath or filelike object whose contents to copy.
@@ -67,7 +69,7 @@ def get_content(self):
         with self.open() as handle:
             return handle.read()
 
-    def set_file(self, file, filename=None):
+    def set_file(self, file, filename: str | pathlib.Path | None = None):
         """Store the content of the file in the node's repository, deleting any other existing objects.
 
         :param file: an absolute filepath or filelike object whose contents to copy
@@ -92,8 +94,7 @@ def set_file(self, file, filename=None):
             except AttributeError:
                 key = self.DEFAULT_FILENAME
 
-        key = filename or key
-
+        key = str(filename) if filename is not None else key
         existing_object_names = self.base.repository.list_object_names()
 
         try:
@@ -126,5 +127,5 @@ def _validate(self):
 
         if [filename] != objects:
             raise exceptions.ValidationError(
-                f'respository files {objects} do not match the `filename` attribute {filename}.'
+                f'respository files {objects} do not match the `filename` attribute `{filename}`.'
             )

tests/orm/nodes/data/test_singlefile.py

@@ -32,7 +32,7 @@ def inner(node, content_reference, filename, open_mode='r'):
         with node.open(mode=open_mode) as handle:
             assert handle.read() == content_reference
 
-        assert node.base.repository.list_object_names() == [filename]
+        assert node.base.repository.list_object_names() == [str(filename)]
 
     return inner
 
@@ -145,16 +145,16 @@ def test_construct_with_path(check_singlefile_content_with_store):
     )
 
 
-def test_construct_with_filename(check_singlefile_content):
+@pytest.mark.parametrize('filename', ('myfile.txt', pathlib.Path('myfile.txt')))
+def test_construct_with_filename(check_singlefile_content_with_store, filename):
     """Test constructing an instance, providing a filename."""
     content_original = 'some testing text\nwith a newline'
-    filename = 'myfile.txt'
 
     # test creating from string
     with io.BytesIO(content_original.encode('utf-8')) as handle:
         node = SinglefileData(file=handle, filename=filename)
 
-    check_singlefile_content(node=node, content_reference=content_original, filename=filename)
+    check_singlefile_content_with_store(node=node, content_reference=content_original, filename=filename)
 
     # test creating from file
     with tempfile.NamedTemporaryFile(mode='wb+') as handle:
@@ -163,7 +163,7 @@ def test_construct_with_filename(check_singlefile_content):
         handle.seek(0)
         node = SinglefileData(file=handle, filename=filename)
 
-    check_singlefile_content(node=node, content_reference=content_original, filename=filename)
+    check_singlefile_content_with_store(node=node, content_reference=content_original, filename=filename)
 
 
 def test_binary_file(check_singlefile_content_with_store):