FIX: rejoin words with the configured word_split_separator (#2593)

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
Co-authored-by: Roman Lutz <romanlutz13@gmail.com>

Author: 3 people

pyrit/converter/word_level_converter.py

@@ -82,13 +82,19 @@ def join_words(self, words: list[str]) -> str:
         """
         Provide a way for subclasses to override the default behavior of joining words.
 
+        Words are rejoined with the same separator they were split on, so a custom
+        ``word_split_separator`` survives the round trip. A ``None`` separator splits on
+        arbitrary whitespace, which has no single representation to restore, so those
+        words are joined with a space.
+
         Args:
             words (list[str]): List of words to join.
 
         Returns:
             str: The joined string.
         """
-        return " ".join(words)
+        separator = " " if self._word_split_separator is None else self._word_split_separator
+        return separator.join(words)
 
     async def convert_async(self, *, prompt: str, input_type: PromptDataType = "text") -> ConverterResult:
         """

tests/unit/converter/test_word_level_converter.py

@@ -30,6 +30,19 @@ async def convert_word_async(self, word: str) -> str:
         return word.upper()
 
 
+class SeparatorWordLevelConverter(WordLevelConverter):
+    """Exposes word_split_separator, mirroring converters like EmojiConverter."""
+
+    def __init__(self, *, word_split_separator=" ", word_selection_strategy=None):
+        super().__init__(
+            word_selection_strategy=word_selection_strategy,
+            word_split_separator=word_split_separator,
+        )
+
+    async def convert_word_async(self, word: str) -> str:
+        return word.upper()
+
+
 class TestWordLevelConverter:
     async def test_convert_async_all_mode(self):
         converter = SimpleWordLevelConverter()
@@ -120,3 +133,30 @@ async def test_default_is_all_words(self):
         assert isinstance(converter._word_selection_strategy, AllWordsSelectionStrategy)
         result = await converter.convert_async(prompt="test prompt")
         assert result.output_text == "TEST PROMPT"
+
+
+class TestWordLevelConverterSeparator:
+    @pytest.mark.parametrize("separator", [",", "|", "-", "::"])
+    async def test_custom_separator_is_preserved(self, separator):
+        converter = SeparatorWordLevelConverter(word_split_separator=separator)
+        prompt = separator.join(["alpha", "beta", "gamma"])
+        result = await converter.convert_async(prompt=prompt)
+        assert result.output_text == separator.join(["ALPHA", "BETA", "GAMMA"])
+
+    async def test_default_space_separator_unchanged(self):
+        converter = SeparatorWordLevelConverter()
+        result = await converter.convert_async(prompt="alpha beta gamma")
+        assert result.output_text == "ALPHA BETA GAMMA"
+
+    async def test_none_separator_joins_with_space(self):
+        converter = SeparatorWordLevelConverter(word_split_separator=None)
+        result = await converter.convert_async(prompt="alpha\tbeta\ngamma")
+        assert result.output_text == "ALPHA BETA GAMMA"
+
+    async def test_custom_separator_preserved_with_partial_selection(self):
+        converter = SeparatorWordLevelConverter(
+            word_split_separator=",",
+            word_selection_strategy=WordIndexSelectionStrategy(indices=[0, 2]),
+        )
+        result = await converter.convert_async(prompt="alpha,beta,gamma")
+        assert result.output_text == "ALPHA,beta,GAMMA"