Fix leading space in surnames after capitalize() with empty middle name

[patchwright]

Summary

After capitalize() is called on a name with any absent attribute, the corresponding *_list attribute becomes [''] instead of []. The most visible symptom is a spurious leading space in surnames (e.g. ' Doe' instead of 'Doe'). The same class of bug also affects suffix_list.

Reproduction

from nameparser import HumanName

n = HumanName('john doe')
n.capitalize()

print(repr(n.surnames))     # ' Doe'   <- leading space
print(n.middle_list)        # ['']    <- should be []
print(n.title_list)         # ['']    <- should be []
print(n.suffix_list)        # ['']    <- should be [] (no suffix present)

The leading space is a real observable artifact, not just an empty-list detail: downstream code that joins or compares surnames silently breaks.

Cause

cap_piece(...) returns '' for an absent name part. Splitting an empty string with an explicit separator always preserves a spurious empty token:

• ''.split(' ') → ['']
• ''.split(', ') → ['']

whereas str.split() with no argument returns [] for an empty string.

Fix

Whitespace-delimited attributes (title, first, middle, last)

Drop the explicit separator — bare .split() correctly returns [] for an empty string:

-        self.title_list = self.cap_piece(self.title, 'title').split(' ')
-        self.first_list = self.cap_piece(self.first, 'first').split(' ')
-        self.middle_list = self.cap_piece(self.middle, 'middle').split(' ')
-        self.last_list = self.cap_piece(self.last, 'last').split(' ')
+        self.title_list = self.cap_piece(self.title, 'title').split()
+        self.first_list = self.cap_piece(self.first, 'first').split()
+        self.middle_list = self.cap_piece(self.middle, 'middle').split()
+        self.last_list = self.cap_piece(self.last, 'last').split()

Suffix

suffix_list must keep its comma delimiter (suffixes are stored as "Ph.D., M.D."), so bare .split() can't be used. Instead, filter empty tokens after splitting:

-        self.suffix_list = self.cap_piece(self.suffix, 'suffix').split(', ')
+        self.suffix_list = [s for s in self.cap_piece(self.suffix, 'suffix').split(', ') if s]

Tests

• Split the original regression test into three focused methods (normal path, force=True path, list invariants)
• Added test_capitalize_title_and_last_only_no_spurious_tokens — exercises empty first_list and middle_list simultaneously
• Added three suffix tests: empty suffix → [], single suffix, multiple suffixes

Full suite: 686 tests OK (20 expected failures).

[patchwright]

Rebased onto master (1f46568) to clear a merge conflict from the test-suite reorg in #165. The monolithic tests.py is gone, so I moved the regression test into tests/test_capitalization.py next to the other capitalize cases. The parser.py fix itself is unchanged (the four .split(" ") calls in capitalize() become .split()). Full suite green locally on 3.13: 670 passed, 4 skipped, 20 xfailed; the new test fails on the unpatched parser with Doe != Doe for john doe, passes with the fix.

[derek73]

Additional fix included: suffix_list spurious '' token

While reviewing this PR, I noticed that suffix_list has the same class of bug: ''.split(', ') returns [''] just like the old ''.split(' ') did for the other attributes. An absent suffix was producing suffix_list == [''] instead of [].

Since .split() (no args) can't be used here — the comma delimiter is load-bearing for multi-suffix names like "Ph.D., M.D." — the fix uses a filtered list comprehension:

-        self.suffix_list = self.cap_piece(self.suffix, 'suffix').split(', ')
+        self.suffix_list = [s for s in self.cap_piece(self.suffix, 'suffix').split(', ') if s]

Three tests added covering the empty-suffix case (the bug), single suffix, and multiple suffixes. Full suite: 686 tests OK.