Fix formatter hook setup and InvalidPath initialization

.pre-commit-config.yaml

@@ -34,6 +34,7 @@ repos:
   rev: ab802050e6e96aaaf7f917fcbc333bb74e2e57f7  # frozen: v1.4.2
   hooks:
   - id: docformatter
+    language_version: python3.12
 - repo: https://github.com/PyCQA/flake8
   rev: d93590f5be797aabb60e3b09f2f52dddb02f349f  # frozen: 7.3.0
   hooks:

src/mdformat/_cli.py

@@ -326,7 +326,8 @@ def separate_core_and_plugin_opts(opts: Mapping) -> tuple[dict, dict]:
 class InvalidPath(Exception):
     """Exception raised when a path does not exist."""
 
-    def __init__(self, path: Path):
+    def __init__(self, path: Path) -> None:
+        super().__init__(path)
         self.path = path
 
 

tests/test_cli.py

@@ -1,11 +1,12 @@
 import os
+import pickle
 import sys
 from unittest.mock import patch
 
 import pytest
 
 import mdformat
-from mdformat._cli import get_plugin_info_str, run, wrap_paragraphs
+from mdformat._cli import InvalidPath, get_plugin_info_str, run, wrap_paragraphs
 from mdformat.plugins import CODEFORMATTERS, PARSER_EXTENSIONS
 from tests.utils import (
     FORMATTED_MARKDOWN,
@@ -92,6 +93,22 @@ def test_invalid_file(capsys):
     assert "does not exist" in captured.err
 
 
+@pytest.mark.parametrize("use_keyword", [False, True])
+def test_invalid_path_exception(tmp_path, use_keyword):
+    path = tmp_path / "missing.md"
+    error = InvalidPath(path=path) if use_keyword else InvalidPath(path)
+
+    assert error.path == path
+    assert error.args == (path,)
+    assert str(error) == str(path)
+
+    restored = pickle.loads(pickle.dumps(error))
+    assert isinstance(restored, InvalidPath)
+    assert restored.path == path
+    assert restored.args == error.args
+    assert str(restored) == str(error)
+
+
 @pytest.mark.skipif(os.name == "nt", reason="No os.mkfifo on windows")
 def test_fifo(tmp_path, capsys):
     fifo_path = tmp_path / "fifo1"