fix: use Self return type for PyProjectData.for_testing

Using Self as the return type for classmethod PyProjectData.for_testing allows
subclasses (like setuptools_scm's extended PyProjectData) to have the correct
return type without needing overrides or type ignore comments.

Changes:
- Added Self import to vcs_versioning._pyproject_reading
- Changed return type from PyProjectData to Self for for_testing and empty methods
- Removed now-unnecessary type: ignore comments in setuptools.py and test_cli.py

This fixes all remaining mypy errors related to PyProjectData type compatibility.

Author: RonnyPfannschmidt

nextgen/vcs-versioning/src/vcs_versioning/_pyproject_reading.py

@@ -3,12 +3,18 @@
 from __future__ import annotations
 
 import logging
+import sys
 import warnings
 
 from dataclasses import dataclass
 from pathlib import Path
 from typing import Sequence
 
+if sys.version_info >= (3, 11):
+    from typing import Self
+else:
+    from typing_extensions import Self
+
 from . import _types as _t
 from ._requirement_cls import extract_package_name
 from ._toml import TOML_RESULT
@@ -48,7 +54,7 @@ def for_testing(
         has_dynamic_version: bool = True,
         build_requires: list[str] | None = None,
         local_scheme: str | None = None,
-    ) -> PyProjectData:
+    ) -> Self:
         """Create a PyProjectData instance for testing purposes."""
         project: TOML_RESULT
         if project_name is not None:
@@ -82,7 +88,7 @@ def for_testing(
     @classmethod
     def empty(
         cls, path: Path = DEFAULT_PYPROJECT_PATH, tool_name: str = DEFAULT_TOOL_NAME
-    ) -> PyProjectData:
+    ) -> Self:
         return cls(
             path=path,
             tool_name=tool_name,

src/setuptools_scm/_integration/setuptools.py

@@ -103,7 +103,7 @@ def version_keyword(
         pyproject_data = read_pyproject(_given_result=_given_pyproject_data)
     except FileNotFoundError:
         log.debug("pyproject.toml not found, proceeding with empty configuration")
-        pyproject_data = PyProjectData.empty()  # type: ignore[assignment]
+        pyproject_data = PyProjectData.empty()
     except InvalidTomlError as e:
         log.debug("Configuration issue in pyproject.toml: %s", e)
         return

testing/test_cli.py

@@ -40,8 +40,7 @@ def _create_version_file_pyproject_data() -> PyProjectData:
         section_present=True, project_present=True, project_name="test"
     )
     data.section["version_file"] = "ver.py"
-    # Type: PyProjectData.for_testing returns the correct type
-    return data  # type: ignore[return-value]
+    return data
 
 
 def get_output(