fix: Handle Git errors when checking for API breaking changes

Issue #144: #144

src/griffe/cli.py

@@ -27,7 +27,7 @@
 from griffe.diff import ExplanationStyle, find_breaking_changes
 from griffe.docstrings.parsers import Parser
 from griffe.encoders import JSONEncoder
-from griffe.exceptions import ExtensionError
+from griffe.exceptions import ExtensionError, GitError
 from griffe.extensions.base import load_extensions
 from griffe.git import _get_latest_tag, _get_repo_root, load_git
 from griffe.loader import GriffeLoader, load
@@ -364,7 +364,11 @@ def check(
 
     search_paths = list(search_paths) if search_paths else []
 
-    against = against or _get_latest_tag(package)
+    try:
+        against = against or _get_latest_tag(package)
+    except GitError as error:
+        print(f"griffe: error: {error}", file=sys.stderr)
+        return 2
     against_path = against_path or package
     repository = _get_repo_root(against_path)
 

src/griffe/exceptions.py

@@ -79,3 +79,7 @@ class ExtensionError(GriffeError):
 
 class ExtensionNotLoadedError(ExtensionError):
     """Exception raised when an extension could not be loaded."""
+
+
+class GitError(GriffeError):
+    """Exception raised for errors related to Git."""

src/griffe/git.py

@@ -19,6 +19,7 @@
 from typing import TYPE_CHECKING, Any, Iterator, Sequence
 
 from griffe import loader
+from griffe.exceptions import GitError
 
 if TYPE_CHECKING:
     from griffe.collections import LinesCollection, ModulesCollection
@@ -47,12 +48,17 @@ def _get_latest_tag(path: str | Path) -> str:
         path = Path(path)
     if not path.is_dir():
         path = path.parent
-    output = subprocess.check_output(
+    process = subprocess.run(
         ["git", "tag", "-l", "--sort=-committerdate"],
         cwd=path,
         text=True,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.STDOUT,
     )
-    return output.strip().split("\n", 1)[0]
+    output = process.stdout.strip()
+    if process.returncode != 0 or not output:
+        raise GitError(f"Cannot list Git tags in {path}: {output or 'no tags'}")
+    return output.split("\n", 1)[0]
 
 
 def _get_repo_root(path: str | Path) -> str:

tests/test_git.py

@@ -8,6 +8,7 @@
 
 import pytest
 
+from griffe.cli import check
 from griffe.dataclasses import Module
 from griffe.git import load_git
 from tests import FIXTURES_DIR
@@ -98,3 +99,8 @@ def test_load_git_errors(git_repo: Path) -> None:
 
     with pytest.raises(ModuleNotFoundError, match="No module named 'not_a_real_module'"):
         load_git("not_a_real_module", ref="v0.2.0", repo=git_repo)
+
+
+def test_git_failures(tmp_path: Path) -> None:
+    """Test failures to use Git."""
+    assert check(tmp_path) == 2