🐛 Fix bug in von-part name parsing (#423)

bibtexparser/middlewares/names.py

@@ -424,11 +424,17 @@ def parse_single_name_into_parts(name, strict=True):
         else:
             lcases = cases[0]
 
-            #
+            def rindex(l, x, default):
+                """Returns the index of the rightmost occurence of x in l."""
+                for i in range(len(l) - 1, -1, -1):
+                    if l[i] == x:
+                        return i
+                return default
+
+            # Check if at least one of the words is lowercase
             if 0 in lcases:
-                split = len(lcases) - lcases[::-1].index(0)
-                if split == len(lcases):
-                    split = 0  # Last cannot be empty.
+                # Excluding the last word, find the index of the last lower word
+                split = rindex(lcases[:-1], 0, -1) + 1
                 parts.von = sections[0][:split]
                 parts.last = sections[0][split:]
 

tests/middleware_tests/test_names.py

@@ -825,6 +825,27 @@ def test_name_splitting_commas_at_higher_brace_level(strict: bool):
         r"Brand\~{a}o, F",
         {"first": ["F"], "von": [], "last": ["Brand\\", "{a}o"], "jr": []},
     ),
+    ###############################################################################
+    #
+    # Group 2 examples from Tame the BeaST
+    #
+    ###############################################################################
+    (
+        r"de la fontaine, Jean",
+        {"first": ["Jean"], "von": ["de", "la"], "last": ["fontaine"], "jr": []},
+    ),
+    (
+        r"De La Fontaine, Jean",
+        {"first": ["Jean"], "von": [], "last": ["De", "La", "Fontaine"], "jr": []},
+    ),
+    (
+        r"De la Fontaine, Jean",
+        {"first": ["Jean"], "von": ["De", "la"], "last": ["Fontaine"], "jr": []},
+    ),
+    (
+        r"de La Fontaine, Jean",
+        {"first": ["Jean"], "von": ["de"], "last": ["La", "Fontaine"], "jr": []},
+    ),
 )