Fix str() scrubbing literal "None" from names when empty_attribute_default is None

docs/release_log.rst

@@ -3,6 +3,7 @@ Release Log
 * 1.3.1 - Unreleased
 
     - Fix invisible Unicode bidirectional control characters (LRM/RLM/ALM, the embedding/override marks, and the isolates U+2066–U+2069) surviving parsing and sticking to ``first``/``last``/etc., so a copy-pasted right-to-left name silently failed equality and dedup. They are now stripped in preprocessing like emoji; disable via ``CONSTANTS.regexes.bidi = False`` (closes #266)
+    - Fix ``str()`` corrupting name text containing the substring ``"None"`` when ``empty_attribute_default`` is ``None`` (e.g. ``"Nonez Smith"`` rendered as ``"z Smith"``): empty attributes are now substituted as ``''`` before the format string is applied, instead of scrubbing the interpolated ``"None"`` from the output afterward (closes #254)
 
 * 1.3.0 - July 5, 2026
 

nameparser/parser.py

@@ -241,9 +241,14 @@ def __setitem__(self, key: str, value: str | list[str] | None) -> None:
     def __str__(self) -> str:
         if self.string_format is not None:
             # string_format = "{title} {first} {middle} {last} {suffix} ({nickname})"
-            _s = self.string_format.format(**self.as_dict())  # noqa: UP032
+            # Empty attributes must render as '' (not empty_attribute_default,
+            # which may be None) so str.format does not interpolate the
+            # literal "None" into the output, which cannot be scrubbed
+            # afterward without corrupting name text containing the same
+            # substring (#254).
+            _s = self.string_format.format(**{k: v or '' for k, v in self.as_dict().items()})
             # remove trailing punctuation from missing nicknames
-            _s = _s.replace(str(self.C.empty_attribute_default), '').replace(" ()", "").replace(" ''", "").replace(' ""', "")
+            _s = _s.replace(" ()", "").replace(" ''", "").replace(' ""', "")
             _s = self.C.regexes.space_before_comma.sub(',', _s)
             return self.collapse_whitespace(_s).strip(', ')
         return " ".join(self)

tests/test_output_format.py

@@ -99,6 +99,21 @@ def test_formating_of_nicknames_in_middle(self) -> None:
         hn.nickname = ''
         self.assertEqual(str(hn), "Rev John A. Kenneth Doe III")
 
+    def test_name_containing_none_substring_with_none_empty_attribute_default(self) -> None:
+        # Regression for #254: with empty_attribute_default = None, __str__
+        # scrubbed the literal string 'None' from the formatted output,
+        # corrupting real name text containing that substring.
+        hn = HumanName("Nonez Smith", None)
+        hn.C.empty_attribute_default = None  # type: ignore[assignment]  # see test_constants.test_empty_attribute_default
+        self.assertEqual(str(hn), "Nonez Smith")
+
+    def test_name_none_as_literal_name_with_none_empty_attribute_default(self) -> None:
+        # Companion to the #254 regression: a name piece that is exactly
+        # 'None' must survive formatting in None-mode.
+        hn = HumanName("None Smith", None)
+        hn.C.empty_attribute_default = None  # type: ignore[assignment]  # see test_constants.test_empty_attribute_default
+        self.assertEqual(str(hn), "None Smith")
+
     def test_empty_field_drops_surrounding_whitespace(self) -> None:
         # issue #139: adjacent whitespace/punctuation should be dropped when a field is empty
         hn = HumanName("John Smith")