gh-123987: Fix NotADirectoryError in NamespaceReader when sentinel present (#124018)

Lib/test/test_importlib/resources/_path.py

@@ -2,15 +2,44 @@ import pathlib
 import functools
 
 from typing import Dict, Union
+from typing import runtime_checkable
+from typing import Protocol
 
 
 ####
-# from jaraco.path 3.4.1
-
-FilesSpec = Dict[str, Union[str, bytes, 'FilesSpec']]  # type: ignore
+# from jaraco.path 3.7.1
 
 
-def build(spec: FilesSpec, prefix=pathlib.Path()):
+class Symlink(str):
+    """
+    A string indicating the target of a symlink.
+    """
+
+
+FilesSpec = Dict[str, Union[str, bytes, Symlink, 'FilesSpec']]
+
+
+@runtime_checkable
+class TreeMaker(Protocol):
+    def __truediv__(self, *args, **kwargs): ...  # pragma: no cover
+
+    def mkdir(self, **kwargs): ...  # pragma: no cover
+
+    def write_text(self, content, **kwargs): ...  # pragma: no cover
+
+    def write_bytes(self, content): ...  # pragma: no cover
+
+    def symlink_to(self, target): ...  # pragma: no cover
+
+
+def _ensure_tree_maker(obj: Union[str, TreeMaker]) -> TreeMaker:
+    return obj if isinstance(obj, TreeMaker) else pathlib.Path(obj)  # type: ignore[return-value]
+
+
+def build(
+    spec: FilesSpec,
+    prefix: Union[str, TreeMaker] = pathlib.Path(),  # type: ignore[assignment]
+):
     """
     Build a set of files/directories, as described by the spec.
 
@@ -25,21 +54,25 @@ def build(spec: FilesSpec, prefix=pathlib.Path()):
     ...             "__init__.py": "",
     ...         },
     ...         "baz.py": "# Some code",
-    ...     }
+    ...         "bar.py": Symlink("baz.py"),
+    ...     },
+    ...     "bing": Symlink("foo"),
     ... }
     >>> target = getfixture('tmp_path')
     >>> build(spec, target)
     >>> target.joinpath('foo/baz.py').read_text(encoding='utf-8')
     '# Some code'
+    >>> target.joinpath('bing/bar.py').read_text(encoding='utf-8')
+    '# Some code'
     """
     for name, contents in spec.items():
-        create(contents, pathlib.Path(prefix) / name)
+        create(contents, _ensure_tree_maker(prefix) / name)
 
 
 @functools.singledispatch
 def create(content: Union[str, bytes, FilesSpec], path):
     path.mkdir(exist_ok=True)
-    build(content, prefix=path)  # type: ignore
+    build(content, prefix=path)  # type: ignore[arg-type]
 
 
 @create.register
@@ -52,5 +85,10 @@ def _(content: str, path):
     path.write_text(content, encoding='utf-8')
 
 
+@create.register
+def _(content: Symlink, path):
+    path.symlink_to(content)
+
+
 # end from jaraco.path
 ####