test: replace placeholder tests with ones that exercise the new regex

The two replaced tests passed via pre-existing collapse_whitespace logic
and didn't exercise space_before_comma at all. Replaced with:
- suffix-present path (regression guard against over-stripping)
- multiple empty fields before comma

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

Author: derek73

tests/test_output_format.py

@@ -109,15 +109,15 @@ def test_empty_field_drops_surrounding_whitespace(self) -> None:
         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_present_suffix_unaffected(self) -> None:
+        hn = HumanName("John Smith Jr")
+        hn.string_format = "{last} {suffix}, {first}"
+        self.assertEqual(str(hn), "Smith Jr, John")
 
-    def test_empty_field_interior_comma_dropped(self) -> None:
+    def test_multiple_empty_fields_before_comma(self) -> None:
         hn = HumanName("John Smith")
-        hn.string_format = "{last}, {suffix} {first}"
-        self.assertEqual(str(hn), "Smith, John")
+        hn.string_format = "{title} {suffix}, {first} {last}"
+        self.assertEqual(str(hn), "John Smith")
 
     def test_remove_emojis(self) -> None:
         hn = HumanName("Sam Smith 😊")