fix: drop whitespace before punctuation when format field is empty (closes #139)

When string_format contains a field like "{last} {suffix}, {first}" and suffix
is absent, the rendered string was "Smith , John" due to the space left between
the empty field and the following comma. Added a post-format substitution step
that strips whitespace before punctuation characters (,;:), consistent with the
existing progressive cleanup pattern in __str__.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: derek73

nameparser/config/regexes.py

@@ -22,6 +22,7 @@
     ("period_not_at_end",re.compile(r'.*\..+$', re.I | re.U)),
     ("emoji",re_emoji),
     ("phd", re.compile(r'\s(ph\.?\s+d\.?)', re.I | re.U)),
+    ("space_before_punct", re.compile(r'\s+([,;:])', re.U)),
 ])
 """
 All regular expressions used by the parser are precompiled and stored in the config.

nameparser/parser.py

@@ -189,6 +189,7 @@ def __str__(self) -> str:
             _s = self.string_format.format(**self.as_dict())
             # remove trailing punctuation from missing nicknames
             _s = _s.replace(str(self.C.empty_attribute_default), '').replace(" ()", "").replace(" ''", "").replace(' ""', "")
+            _s = self.C.regexes.space_before_punct.sub(r'\1', _s)
             return self.collapse_whitespace(_s).strip(', ')
         return " ".join(self)
 

tests/test_output_format.py

@@ -103,6 +103,22 @@ def test_formating_of_nicknames_in_middle(self) -> None:
         hn.nickname = ''
         self.assertEqual(str(hn), "Rev John A. Kenneth Doe III")
 
+    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")
+        hn.string_format = "{last} {suffix}, {first}"
+        self.assertEqual(str(hn), "Smith, John")
+
+    def test_empty_field_drops_surrounding_punctuation(self) -> None:
+        hn = HumanName("John Smith")
+        hn.string_format = "{title} {first} {last}"
+        self.assertEqual(str(hn), "John Smith")
+
+    def test_empty_field_interior_comma_dropped(self) -> None:
+        hn = HumanName("John Smith")
+        hn.string_format = "{last}, {suffix} {first}"
+        self.assertEqual(str(hn), "Smith, John")
+
     def test_remove_emojis(self) -> None:
         hn = HumanName("Sam Smith 😊")
         self.m(hn.first, "Sam", hn)