improve coverage for cases where the loop bodies are skipped

tests/test_page_labels.py

@@ -1,10 +1,12 @@
 """Test the pypdf._page_labels module."""
 from io import BytesIO
+from pathlib import Path
 
 import pytest
 
 from pypdf import PdfReader
 from pypdf._page_labels import (
+ get_label_from_nums,
  index2label,
  number2lowercase_letter,
  number2lowercase_roman_numeral,
@@ -15,6 +17,7 @@
  nums_next,
 )
 from pypdf.generic import (
+ ArrayObject,
  DictionaryObject,
  NameObject,
  NullObject,
@@ -23,6 +26,10 @@
 
 from . import get_data_from_url
 
+TESTS_ROOT = Path(__file__).parent.resolve()
+PROJECT_ROOT = TESTS_ROOT.parent
+RESOURCE_ROOT = PROJECT_ROOT / "resources"
+
 
 @pytest.mark.parametrize(
  ("number", "expected"),
@@ -119,3 +126,19 @@ def test_index2label_kids():
  # whole list itself here.
  expected.remove(x)
  assert r.page_labels == expected
+
+
+def test_get_label_from_nums__empty_nums_list():
+ dictionary_object = DictionaryObject()
+ dictionary_object[NameObject("/Nums")] = ArrayObject()
+ assert get_label_from_nums(dictionary_object, 13) == "14"
+
+
+def test_index2label__empty_kids_list():
+ reader = PdfReader(RESOURCE_ROOT / "crazyones.pdf")
+ number_tree = DictionaryObject()
+ number_tree[NameObject("/Kids")] = ArrayObject()
+ root = reader.root_object
+ root[NameObject("/PageLabels")] = number_tree
+
+ assert index2label(reader, 42) == "43"