Enhance testing capabilities for pyproject reading and version inference

- Introduced `_given_result` parameter in `read_pyproject`
- expand the setuptools integration points with it
- Improved error handling by allowing direct injection of `PyProjectData`, `InvalidTomlError`, or `FileNotFoundError` for better testability.

Author: RonnyPfannschmidt

src/setuptools_scm/_integration/pyproject_reading.py

@@ -7,8 +7,10 @@
 from typing import Sequence
 
 from .. import _log
+from .. import _types as _t
 from .._requirement_cls import extract_package_name
 from .toml import TOML_RESULT
+from .toml import InvalidTomlError
 from .toml import read_toml_content
 
 log = _log.log.getChild("pyproject_reading")
@@ -126,7 +128,28 @@ def read_pyproject(
     path: Path = Path("pyproject.toml"),
     tool_name: str = "setuptools_scm",
     canonical_build_package_name: str = "setuptools-scm",
+    _given_result: _t.GivenPyProjectResult = None,
 ) -> PyProjectData:
+    """Read and parse pyproject configuration.
+
+    This function supports dependency injection for tests via `_given_result`.
+
+    Parameters:
+    - path: Path to the pyproject file
+    - tool_name: The tool section name (default: `setuptools_scm`)
+    - canonical_build_package_name: Normalized build requirement name
+    - _given_result: Optional testing hook. Can be:
+        - PyProjectData: returned directly
+        - InvalidTomlError | FileNotFoundError: raised directly
+        - None: read from filesystem
+    """
+
+    if _given_result is not None:
+        if isinstance(_given_result, PyProjectData):
+            return _given_result
+        if isinstance(_given_result, (InvalidTomlError, FileNotFoundError)):
+            raise _given_result
+
     defn = read_toml_content(path)
 
     requires: list[str] = defn.get("build-system", {}).get("requires", [])

src/setuptools_scm/_integration/setuptools.py

@@ -9,6 +9,7 @@
 
 import setuptools
 
+from .. import _types as _t
 from .pyproject_reading import PyProjectData
 from .pyproject_reading import read_pyproject
 from .setup_cfg import _dist_name_from_legacy
@@ -68,7 +69,7 @@ def version_keyword(
     keyword: str,
     value: bool | dict[str, Any] | Callable[[], dict[str, Any]],
     *,
-    _given_pyproject_data: PyProjectData | None = None,
+    _given_pyproject_data: _t.GivenPyProjectResult = None,
 ) -> None:
     """apply version infernce when setup(use_scm_version=...) is used
     this takes priority over the finalize_options based version
@@ -87,20 +88,15 @@ def version_keyword(
 
     was_set_by_infer = getattr(dist, "_setuptools_scm_version_set_by_infer", False)
 
-    # Get pyproject data
-    if _given_pyproject_data is not None:
-        pyproject_data = _given_pyproject_data
-    else:
-        try:
-            pyproject_data = read_pyproject()
-        except FileNotFoundError:
-            log.debug("pyproject.toml not found, proceeding with empty configuration")
-            pyproject_data = PyProjectData.empty(
-                Path("pyproject.toml"), "setuptools_scm"
-            )
-        except InvalidTomlError as e:
-            log.debug("Configuration issue in pyproject.toml: %s", e)
-            return
+    # Get pyproject data (support direct injection for tests)
+    try:
+        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(Path("pyproject.toml"), "setuptools_scm")
+    except InvalidTomlError as e:
+        log.debug("Configuration issue in pyproject.toml: %s", e)
+        return
 
     result = get_version_inference_config(
         dist_name=dist_name,
@@ -114,7 +110,9 @@ def version_keyword(
 
 
 def infer_version(
-    dist: setuptools.Distribution, *, _given_pyproject_data: PyProjectData | None = None
+    dist: setuptools.Distribution,
+    *,
+    _given_pyproject_data: _t.GivenPyProjectResult = None,
 ) -> None:
     """apply version inference from the finalize_options hook
     this is the default for pyproject.toml based projects that don't use the use_scm_version keyword
@@ -127,17 +125,14 @@ def infer_version(
 
     dist_name = _dist_name_from_legacy(dist)
 
-    if _given_pyproject_data is not None:
-        pyproject_data = _given_pyproject_data
-    else:
-        try:
-            pyproject_data = read_pyproject()
-        except FileNotFoundError:
-            log.debug("pyproject.toml not found, skipping infer_version")
-            return
-        except InvalidTomlError as e:
-            log.debug("Configuration issue in pyproject.toml: %s", e)
-            return
+    try:
+        pyproject_data = read_pyproject(_given_result=_given_pyproject_data)
+    except FileNotFoundError:
+        log.debug("pyproject.toml not found, skipping infer_version")
+        return
+    except InvalidTomlError as e:
+        log.debug("Configuration issue in pyproject.toml: %s", e)
+        return
 
     result = get_version_inference_config(
         dist_name=dist_name,

src/setuptools_scm/_types.py

@@ -18,6 +18,8 @@
         from typing_extensions import TypeAlias
 
     from . import version
+    from ._integration.pyproject_reading import PyProjectData
+    from ._integration.toml import InvalidTomlError
 
 PathT: TypeAlias = Union["os.PathLike[str]", str]
 
@@ -29,3 +31,8 @@
 
 # Git pre-parse function types
 GIT_PRE_PARSE: TypeAlias = Union[str, None]
+
+# Testing injection types for configuration reading
+GivenPyProjectResult: TypeAlias = Union[
+    "PyProjectData", "InvalidTomlError", FileNotFoundError, None
+]