Update util.abs_path to return Path for Paths (#4310)

Also return empty string instead of None where it would have before.

This allows us to always consume the output, without doing type
shenanigans after, and gradually move to Path where it's convenient.

.pre-commit-config.yaml

@@ -23,8 +23,6 @@ repos:
     rev: v3.1.0
     hooks:
       - id: add-trailing-comma
-        args:
-          - --py36-plus
 
   - repo: https://github.com/Lucas-C/pre-commit-hooks.git
     rev: v1.5.5

pyproject.toml

@@ -356,14 +356,14 @@ verbosity_assertions = 2
 [tool.ruff]
 builtins = ["__"]
 cache-dir = "./.cache/.ruff"
-external = [
-  "DOC" # pydoclint
-]
 fix = true
 line-length = 100
 target-version = "py310"
 
 [tool.ruff.lint]
+external = [
+  "DOC" # pydoclint
+]
 select = ["ALL"]
 
 [tool.ruff.lint.flake8-pytest-style]

src/molecule/command/base.py

@@ -252,7 +252,7 @@ def get_configs(
     scenario_paths = filter_ignored_scenarios(scenario_paths)
     configs = [
         config.Config(
-            molecule_file=util.abs_path(c),  # type: ignore[arg-type]
+            molecule_file=util.abs_path(c),
             args=args,
             command_args=command_args,
             ansible_args=ansible_args,

src/molecule/provisioner/ansible.py

@@ -27,6 +27,7 @@
 import os
 import shutil
 
+from pathlib import Path
 from typing import Any
 
 from ansible_compat.ports import cached_property
@@ -520,8 +521,8 @@ def default_env(self):  # type: ignore[no-untyped-def]  # noqa: ANN201, D102
             os.environ,
             {
                 "ANSIBLE_CONFIG": self._config.provisioner.config_file,
-                "ANSIBLE_ROLES_PATH": ":".join(roles_path_list),  # type: ignore[arg-type]
-                self._config.ansible_collections_path: ":".join(collections_path_list),  # type: ignore[arg-type]
+                "ANSIBLE_ROLES_PATH": ":".join(roles_path_list),
+                self._config.ansible_collections_path: ":".join(collections_path_list),
                 "ANSIBLE_LIBRARY": ":".join(self._get_modules_directories()),
                 "ANSIBLE_FILTER_PLUGINS": ":".join(
                     self._get_filter_plugins_directories(),
@@ -804,17 +805,13 @@ def _add_or_update_vars(self):  # type: ignore[no-untyped-def]  # noqa: ANN202
                 vars_target = self.group_vars
 
             if vars_target:
-                target_vars_directory = os.path.join(  # noqa: PTH118
-                    self.inventory_directory,
-                    target,
-                )
-
-                if not os.path.isdir(util.abs_path(target_vars_directory)):  # type: ignore[arg-type]  # noqa: PTH112
-                    os.mkdir(util.abs_path(target_vars_directory))  # type: ignore[arg-type]  # noqa: PTH102
+                target_vars_directory = util.abs_path(Path(self.inventory_directory) / target)
+                if not target_vars_directory.is_dir():
+                    target_vars_directory.mkdir()
 
                 for target in vars_target:  # noqa: PLW2901
                     target_var_content = vars_target[target]
-                    path = os.path.join(util.abs_path(target_vars_directory), target)  # type: ignore[arg-type]  # noqa: PTH118
+                    path = target_vars_directory / target
                     util.write_file(path, util.safe_dump(target_var_content))
 
     def _write_inventory(self):  # type: ignore[no-untyped-def]  # noqa: ANN202

src/molecule/util.py

@@ -29,7 +29,7 @@
 
 from pathlib import Path
 from subprocess import CalledProcessError, CompletedProcess
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, overload
 
 import jinja2
 import yaml
@@ -394,7 +394,15 @@ def filter_verbose_permutation(options: dict[str, Any]) -> dict[str, Any]:
     return {k: options[k] for k in options if not re.match("^[v]+$", k)}
 
 
-def abs_path(path: str | Path | None) -> str | None:
+@overload
+def abs_path(path: Path) -> Path: ...
+
+
+@overload
+def abs_path(path: str | None) -> str: ...
+
+
+def abs_path(path: str | Path | None) -> str | Path:
     """Return absolute path.
 
     Args:
@@ -403,12 +411,15 @@ def abs_path(path: str | Path | None) -> str | None:
     Returns:
         Absolute path of path.
     """
-    if path:
-        if isinstance(path, str):
-            path = Path(path)
+    if not path:
+        return ""
 
-        return str(path.resolve())
-    return None
+    output_type = type(path)
+    if isinstance(path, str):
+        path = Path(path)
+    path = path.resolve()
+
+    return output_type(path)
 
 
 def merge_dicts(a: _T, b: _T) -> _T:

tests/unit/test_util.py

@@ -23,6 +23,7 @@
 import os
 import warnings
 
+from pathlib import Path
 from typing import TYPE_CHECKING
 
 import pytest
@@ -36,7 +37,6 @@
 
 if TYPE_CHECKING:
     from collections.abc import MutableMapping
-    from pathlib import Path
     from typing import Any
     from unittest.mock import Mock
 
@@ -327,9 +327,15 @@ def test_abs_path() -> None:
     assert util.abs_path(test_dir) == "/foo"
 
 
+def test_abs_path_with_path() -> None:
+    """Test the `abs_path` function."""
+    test_dir = Path("/foo/../foo")
+    assert util.abs_path(test_dir) == Path("/foo")
+
+
 def test_abs_path_with_empty_path() -> None:
     """Test the `abs_path` function with an empty path."""
-    assert util.abs_path("") is None
+    assert util.abs_path("") == ""
 
 
 @pytest.mark.parametrize(