Refs #30686 -- Fixed text truncation for negative or zero lengths.

django/utils/text.py

@@ -104,6 +104,8 @@ class Truncator(SimpleLazyObject):
         """
         self._setup()
         length = int(num)
+        if length <= 0:
+            return ""
         text = unicodedata.normalize("NFC", self._wrapped)
 
         # Calculate the length to truncate to (max length - end_text length)
@@ -144,6 +146,8 @@ class Truncator(SimpleLazyObject):
         """
         self._setup()
         length = int(num)
+        if length <= 0:
+            return ""
         if html:
             return self._truncate_html(length, truncate, self._wrapped, length, True)
         return self._text_words(length, truncate)

tests/template_tests/filter_tests/test_truncatechars_html.py

@@ -8,7 +8,7 @@ class FunctionTests(SimpleTestCase):
             truncatechars_html(
                 '<p>one <a href="#">two - three <br>four</a> five</p>', 0
             ),
-            "…",
+            "",
         )
 
     def test_truncate(self):

tests/utils_tests/test_text.py

@@ -89,7 +89,7 @@ class TestUtilsText(SimpleTestCase):
 
         # Make a best effort to shorten to the desired length, but requesting
         # a length shorter than the ellipsis shouldn't break
-        self.assertEqual("…", text.Truncator("asdf").chars(0))
+        self.assertEqual("...", text.Truncator("asdf").chars(1, truncate="..."))
         # lazy strings are handled correctly
         self.assertEqual(
             text.Truncator(lazystr("The quick brown fox")).chars(10), "The quick…"
@@ -123,6 +123,8 @@ class TestUtilsText(SimpleTestCase):
             "…",
             truncator.chars(1, html=True),
         )
+        self.assertEqual("", truncator.chars(0, html=True))
+        self.assertEqual("", truncator.chars(-1, html=True))
         self.assertEqual(
             '<p id="par"><strong><em>The qu....</em></strong></p>',
             truncator.chars(10, "....", html=True),
@@ -206,6 +208,8 @@ class TestUtilsText(SimpleTestCase):
             lazystr("The quick brown fox jumped over the lazy dog.")
         )
         self.assertEqual("The quick brown fox…", truncator.words(4))
+        self.assertEqual("", truncator.words(0))
+        self.assertEqual("", truncator.words(-1))
 
     def test_truncate_html_words(self):
         truncator = text.Truncator(