fix: Allow adding PathLike object to index

Close #1382

Author: Ruben DI BATTISTA

git/index/base.py

@@ -617,11 +617,11 @@ def _preprocess_add_items(
         paths = []
         entries = []
         # if it is a string put in list
-        if isinstance(items, str):
+        if isinstance(items, (str, os.PathLike)):
             items = [items]
 
         for item in items:
-            if isinstance(item, str):
+            if isinstance(item, (str, os.PathLike)):
                 paths.append(self._to_relative_path(item))
             elif isinstance(item, (Blob, Submodule)):
                 entries.append(BaseIndexEntry.from_blob(item))

test/test_index.py

@@ -37,6 +37,8 @@
 import os.path as osp
 from git.cmd import Git
 
+from pathlib import Path
+
 HOOKS_SHEBANG = "#!/usr/bin/env sh\n"
 
 is_win_without_bash = is_win and not shutil.which("bash.exe")
@@ -943,3 +945,12 @@ def test_commit_msg_hook_fail(self, rw_repo):
                 assert str(err)
         else:
             raise AssertionError("Should have caught a HookExecutionError")
+
+    @with_rw_repo('HEAD')
+    def test_index_add_pathlike(self, rw_repo):
+        git_dir = Path(rw_repo.git_dir)
+
+        file = git_dir / "file.txt"
+        file.touch()
+
+        rw_repo.index.add(file)