Ticket #12506: diff.diff

django/utils/functional.py

@@ -167 +167 @@
             for resultclass in resultclasses:
                 cls.__dispatch[resultclass] = {}
                 for (k, v) in resultclass.__dict__.items():
+                    # All __promise__ return the same wrapper method, but they
+                    # also do setup, inserting the method into the dispatch
+                    # dict.
+                    meth = cls.__promise__(resultclass, k, v)
                     if hasattr(cls, k):
                         continue
-                    setattr(cls, k, cls.__promise__(resultclass, k, v))
+                    setattr(cls, k, meth)
             cls._delegate_str = str in resultclasses
             cls._delegate_unicode = unicode in resultclasses
             assert not (cls._delegate_str and cls._delegate_unicode), "Cannot call lazy() with both str and unicode return types."

new file tests/regressiontests/utils/functional.py

@@ +1 @@
+from unittest import TestCase
+
+from django.utils.functional import lazy
+
+
+class FunctionalTestCase(TestCase):
+    def test_lazy(self):
+        t = lazy(lambda: tuple(range(3)), list, tuple)
+        for a, b in zip(t(), range(3)):
+            self.assertEqual(a, b)

tests/regressiontests/utils/tests.py

@@ -12 +12 @@
 import itercompat
 
 from decorators import DecoratorFromMiddlewareTests
+from functional import FunctionalTestCase
 
 # We need this because "datastructures" uses sorted() and the tests are run in
 # the scope of this module.