Fix #2118: Slice filter no longer adds extra fill_with items

src/jinja2/filters.py

@@ -1089,7 +1089,11 @@ def sync_do_slice(
         end = offset + (slice_number + 1) * items_per_slice
         tmp = seq[start:end]
 
-        if fill_with is not None and slice_number >= slices_with_extra:
+        if (
+            fill_with is not None
+            and slice_number >= slices_with_extra
+            and slices_with_extra != 0
+        ):
             tmp.append(fill_with)
 
         yield tmp

tests/test_filters.py

@@ -78,6 +78,28 @@ def test_slice(self, env):
             "[[0, 1, 2, 3], [4, 5, 6, 'X'], [7, 8, 9, 'X']]"
         )
 
+    def test_slice_even_division_with_fill(self, env):
+        """Regression test for #2118: fill_with should not add items when
+        the slice count evenly divides the iterable length."""
+        tmpl = env.from_string("{{ foo|slice(4, 'foo')|list }}")
+        out = tmpl.render(foo=[1, 2, 3, 4])
+        assert out == "[[1], [2], [3], [4]]"
+
+    def test_slice_even_division_no_fill(self, env):
+        tmpl = env.from_string("{{ foo|slice(2)|list }}")
+        out = tmpl.render(foo=[1, 2, 3, 4])
+        assert out == "[[1, 2], [3, 4]]"
+
+    def test_slice_uneven_with_fill(self, env):
+        tmpl = env.from_string("{{ foo|slice(2, 'x')|list }}")
+        out = tmpl.render(foo=[1, 2, 3])
+        assert out == "[[1, 2], [3, 'x']]"
+
+    def test_slice_uneven_five_items(self, env):
+        tmpl = env.from_string("{{ foo|slice(3, 'x')|list }}")
+        out = tmpl.render(foo=[1, 2, 3, 4, 5])
+        assert out == "[[1, 2], [3, 4], [5, 'x']]"
+
     def test_escape(self, env):
         tmpl = env.from_string("""{{ '<">&'|escape }}""")
         out = tmpl.render()