Add subclass of pathlib.Path for existing directories

src/jcloud_docsgen/_utils.py

@@ -0,0 +1,36 @@
+# Copyright 2026 jCloud Services GbR
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+'''
+The utilities for jcloud_docsgen
+'''
+
+import pathlib
+import os
+import errno
+
+class ExistingDirectory(pathlib.Path):
+    '''
+    pathlib.Path subclass that is a directory
+
+    ExistingDirectory represents a filesystem path but it also checks
+    whether the path exists and is not a file but a directory. It
+    inherits from pathlib.Path.
+    '''
+    def __init__(self, path, *args, **kwargs) -> None:
+        if not os.path.exists(path):
+            raise FileNotFoundError(errno.ENOENT, 'no such file or directory', path)
+        if not os.path.isdir(path):
+            raise NotADirectoryError(errno.ENOTDIR, 'not a directory', path)
+        super().__init__(*(path, *args), **kwargs)

tests/unit/_utils/test_ExistingDirectory.py

@@ -0,0 +1,28 @@
+from src.jcloud_docsgen._utils import ExistingDirectory
+import pytest
+import pathlib
+
+@pytest.mark.parametrize('path,expected', [
+    ('tests/unit/_utils/test_directory/', 'tests/unit/_utils/test_directory'),
+    ('tests/unit/_utils/test_directory', 'tests/unit/_utils/test_directory'),
+    ('tests/unit/_utils/', 'tests/unit/_utils'),
+    ('tests/unit/_utils', 'tests/unit/_utils'),
+    ('/', '/'),
+    ('./', '.'),
+    ('.', '.'),
+    ('../', '..'),
+    ('..', '..'),
+])
+def test_ExistingDirectory(path, expected):
+    assert ExistingDirectory(path).as_posix() == expected
+
+@pytest.mark.parametrize('path,expected_exception,expected_exception_message', [
+    ('tests/unit/_utils/does_not_exist/', FileNotFoundError, '[Errno 2] no such file or directory: \'tests/unit/_utils/does_not_exist/\''),
+    ('tests/unit/_utils/does_not_exist', FileNotFoundError, '[Errno 2] no such file or directory: \'tests/unit/_utils/does_not_exist\''),
+    ('', FileNotFoundError, '[Errno 2] no such file or directory: \'\''),
+    ('README.md', NotADirectoryError, '[Errno 20] not a directory: \'README.md\''),
+])
+def test_ExistingDirectory_exceptions(path, expected_exception, expected_exception_message):
+    with pytest.raises(expected_exception) as exc_info:
+        ExistingDirectory(path)
+    assert str(exc_info.value) == expected_exception_message