config: Add Config.books_repo() method.

conservancy_beancount/config.py

@@ -22,6 +22,7 @@ import os
 import re
 import urllib.parse as urlparse
 
+import git  # type:ignore[import]
 import requests.auth
 import rt
 
@@ -128,6 +129,16 @@ class Config:
     def books_path(self) -> Optional[Path]:
         return self._abspath(self.file_config['Beancount'], 'books dir')
 
+    def books_repo(self) -> Optional[git.Repo]:
+        """Return a git.Repo object for the books directory
+
+        Returns None if the books directory is not a valid Git repository.
+        """
+        try:
+            return git.Repo(self.file_config['Beancount']['books dir'])
+        except (KeyError, git.exc.GitError):
+            return None
+
     def cache_dir_path(self, name: str='conservancy_beancount') -> Optional[Path]:
         cache_root = self._path_from_environ('XDG_CACHE_HOME')
         return (

setup.py

@@ -13,6 +13,7 @@ setup(
     install_requires=[
         'babel>=2.6',  # Debian:python3-babel
         'beancount>=2.2',  # Debian:beancount
+        'GitPython>=2.0',  # Debian:python3-git
         # 1.4.1 crashes when trying to save some documents.
         'odfpy>=1.4.0,!=1.4.1',  # Debian:python3-odf
         'PyYAML>=3.0',  # Debian:python3-yaml

tests/test_config.py

@@ -20,6 +20,8 @@ import operator
 import os
 import re
 
+import git
+
 from pathlib import Path
 
 import pytest
@@ -422,3 +424,19 @@ def test_books_loader():
 
 def test_books_loader_without_books():
     assert config_mod.Config().books_loader() is None
+
+def test_books_repo(tmp_path):
+    repo_path = tmp_path / 'books_repo'
+    expected = git.Repo.init(repo_path)
+    config = config_mod.Config()
+    config.load_string(f'[Beancount]\nbooks dir = {repo_path}')
+    assert config.books_repo() == expected
+
+def test_books_repo_no_dir():
+    config = config_mod.Config()
+    assert config.books_repo() is None
+
+def test_books_dir_not_repo():
+    config = config_mod.Config()
+    config.load_string(f'[Beancount]\nbooks dir = {os.devnull}')
+    assert config.books_repo() is None