Add function to ensure a non-empty string.

docs/CHANGELOG.md

@@ -21,4 +21,5 @@
 - Add class for Python modules
 - Add feature to get the signature representation of a Python function argument
 - Add class for Python docstrings
-- Add feature to parse Python docstrings
+- Add feature to parse Python docstrings
+- Add function to ensure a non-empty string.

src/jcloud_docsgen/utils.py

@@ -127,4 +127,28 @@ def assert_that_is_instance(obj: object, class_or_tuple: Union[type, types.Union
             exception_message_expected += human_readable_list(_list_type_names(class_or_tuple), 'or', '\'')
         else:
             exception_message_expected = '\'' + class_or_tuple.__name__ + '\''
-        raise TypeError(f'expected {exception_message_expected}, got \'{type(obj).__name__}\'')
+        raise TypeError(f'expected {exception_message_expected}, got \'{type(obj).__name__}\'')
+    
+def non_empty_str(value: Union[str, None]) -> Union[str, None]:
+    '''
+    Returns the value or ``None``.
+
+    Returns the value if it is not empty and not `Ǹone``; otherwise,
+    returns ``None``.
+    Please note: values are stripped, i. e. if the value consists only
+                 of spaces, it is also considered empty.
+
+    :param value: The value.
+    :type value: Union[str, None]
+
+    :return: The value or ``None``.
+    :rtype: Union[str, None]
+    '''
+
+    if value is None:
+        return None
+    
+    if value.strip() == '':
+        return None
+
+    return value

tests/unit/utils/test_non_empty_str.py

@@ -0,0 +1,30 @@
+# 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.
+
+from src.jcloud_docsgen.utils import non_empty_str
+import pytest
+
+@pytest.mark.parametrize('value,expected', [
+    (None, None),
+    ('', None),
+    (' ', None),
+    ('  ', None),
+    ('   ', None),
+    (' a ', ' a '),
+    (' a', ' a'),
+    ('a ', 'a '),
+    ('a', 'a'),
+])
+def test_non_empty_str(value, expected):
+    assert non_empty_str(value) == expected