Prevent random filter from being inlined

jinja2/filters.py

@@ -10,8 +10,8 @@
 """
 import re
 import math
+import random
 
-from random import choice
 from operator import itemgetter
 from itertools import groupby
 from jinja2.utils import Markup, escape, pformat, urlize, soft_unicode, \
@@ -360,13 +360,13 @@ def do_last(environment, seq):
         return environment.undefined('No last item, sequence was empty.')
 
 
-@environmentfilter
-def do_random(environment, seq):
+@contextfilter
+def do_random(context, seq):
     """Return a random item from the sequence."""
     try:
-        return choice(seq)
+        return random.choice(seq)
     except IndexError:
-        return environment.undefined('No random item, sequence was empty.')
+        return context.environment.undefined('No random item, sequence was empty.')
 
 
 def do_filesizeformat(value, binary=False):

tests/test_filters.py

@@ -8,6 +8,7 @@
     :copyright: (c) 2010 by the Jinja Team.
     :license: BSD, see LICENSE for more details.
 """
+import random
 import pytest
 from jinja2 import Markup, Environment
 from jinja2._compat import text_type, implements_to_string
@@ -177,12 +178,18 @@ def test_pprint(self, env):
         data = list(range(1000))
         assert tmpl.render(data=data) == pformat(data)
 
-    def test_random(self, env):
+    def test_random1(self, env):
         tmpl = env.from_string('''{{ seq|random }}''')
         seq = list(range(100))
         for _ in range(10):
             assert int(tmpl.render(seq=seq)) in seq
 
+    def test_random2(self, env, monkeypatch):
+        monkeypatch.setattr(random, 'choice', lambda seq: seq[0])
+        tmpl = env.from_string('''{{ range(100)|random }}''')
+        monkeypatch.setattr(random, 'choice', lambda seq: seq[2])
+        assert tmpl.render() == '2'
+
     def test_reverse(self, env):
         tmpl = env.from_string('{{ "foobar"|reverse|join }}|'
                                '{{ [1, 2, 3]|reverse|list }}')