From b8c0d21b3f1b3714c1e188836fc84ca8211a7e56 Mon Sep 17 00:00:00 2001
From: santhreal <64453045+santhreal@users.noreply.github.com>
Date: Fri, 17 Jul 2026 22:30:43 -0700
Subject: [PATCH] Fix smart_truncate ValueError on empty separator

word_boundary truncation splits on separator; an empty separator is
invalid for str.split and should hard-truncate instead.
---
 slugify/slugify.py |  3 ++-
 test.py            | 11 +++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/slugify/slugify.py b/slugify/slugify.py
index 9b5f27f..54843b6 100644
--- a/slugify/slugify.py
+++ b/slugify/slugify.py
@@ -49,7 +49,8 @@ def smart_truncate(
     if len(string) < max_length:
         return string
 
-    if not word_boundary:
+    # Empty separator cannot split words; fall back to hard truncate.
+    if not word_boundary or not separator:
         return string[:max_length].strip(separator)
 
     if separator not in string:
diff --git a/test.py b/test.py
index fcec4b6..743a6df 100644
--- a/test.py
+++ b/test.py
@@ -540,6 +540,17 @@ def test_smart_truncate_no_seperator(self):
         r = smart_truncate(txt, max_length=100, separator='_')
         self.assertEqual(r, txt)
 
+    def test_smart_truncate_empty_separator_word_boundary(self):
+        txt = 'helloworld'
+        self.assertEqual(
+            smart_truncate(txt, max_length=5, word_boundary=True, separator=''),
+            'hello',
+        )
+        self.assertEqual(
+            slugify('hello world', max_length=5, word_boundary=True, separator=''),
+            'hello',
+        )
+
 
 PY3 = sys.version_info.major == 3