fix: for using an empty character as label_suffix separator

Closes #138

CHANGELOG.md

@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- the ability to use an empty string as the separator in `config.database.format.label_suffix` (#138)
+
 
 ## [5.0.0] - 2024-04-28
 

src/cobib/config/config.py

@@ -607,7 +607,12 @@ def trim_label(label: str, separator: str, type_: LabelSuffix) -> tuple[str, int
         suffix_value = 0
 
         # try split the suffix from the label using the provided separator
-        *pieces, suffix = label.split(separator)
+        if separator:
+            *pieces, suffix = label.split(separator)
+        else:
+            # no character is used for separation, we simply fall back to using the last one
+            suffix = label[-1]
+            pieces = [label[:-1]]
 
         if pieces:
             # piece together the left-over raw label without its suffix

tests/database/disambiguation_database.yaml

@@ -40,3 +40,10 @@ Author2022:
   title: Some entry
   year: 2022
 ...
+---
+Author2022a:
+  ENTRYTYPE: book
+  author: Author
+  title: Some entry a
+  year: 2022
+...

tests/database/test_database.py

@@ -143,6 +143,9 @@ def test_database_rename() -> None:
         [(".", LabelSuffix.ALPHA), "test.a"],
         [(".", LabelSuffix.CAPITAL), "test.A"],
         [(".", LabelSuffix.NUMERIC), "test.1"],
+        [("", LabelSuffix.ALPHA), "testa"],
+        [("", LabelSuffix.CAPITAL), "testA"],
+        [("", LabelSuffix.NUMERIC), "test1"],
     ],
 )
 def test_database_disambiguate_label(label_suffix: tuple[str, LabelSuffix], expected: str) -> None:
@@ -181,6 +184,11 @@ def test_database_disambiguate_label(label_suffix: tuple[str, LabelSuffix], expe
             ("_", LabelSuffix.NUMERIC),
             ({"Author2021", "Author2021_2"}, set()),
         ],
+        [
+            "Author2022",
+            ("", LabelSuffix.ALPHA),
+            ({"Author2022", "Author2022a"}, set()),
+        ],
     ],
 )
 def test_find_related_labels(