Fixed #20296 -- Allowed SafeData and EscapeData to be lazy

2 files changed, 60 insertions, 3 deletions

diff --git a/django/utils/safestring.py b/django/utils/safestring.py
index 07e0bf4cea..3774012d32 100644
--- a/django/utils/safestring.py
+++ b/django/utils/safestring.py
@@ -4,7 +4,7 @@ without further escaping in HTML. Marking something as a "safe string" means
 that the producer of the string has already turned characters that should not
 be interpreted by the HTML engine (e.g. '<') into the appropriate entities.
 """
-from django.utils.functional import curry, Promise
+from django.utils.functional import curry, Promise, allow_lazy
 from django.utils import six
 
 class EscapeData(object):
@@ -14,13 +14,13 @@ class EscapeBytes(bytes, EscapeData):
     """
     A byte string that should be HTML-escaped when output.
     """
-    pass
+    __new__ = allow_lazy(bytes.__new__, bytes)
 
 class EscapeText(six.text_type, EscapeData):
     """
     A unicode string object that should be HTML-escaped when output.
     """
-    pass
+    __new__ = allow_lazy(six.text_type.__new__, six.text_type)
 
 if six.PY3:
     EscapeString = EscapeText
@@ -37,6 +37,8 @@ class SafeBytes(bytes, SafeData):
     A bytes subclass that has been specifically marked as "safe" (requires no
     further escaping) for HTML output purposes.
     """
+    __new__ = allow_lazy(bytes.__new__, bytes)
+
     def __add__(self, rhs):
         """
         Concatenating a safe byte string with another safe byte string or safe
@@ -69,6 +71,8 @@ class SafeText(six.text_type, SafeData):
     A unicode (Python 2) / str (Python 3) subclass that has been specifically
     marked as "safe" for HTML output purposes.
     """
+    __new__ = allow_lazy(six.text_type.__new__, six.text_type)
+
     def __add__(self, rhs):
         """
         Concatenating a safe unicode string with another safe byte string or
diff --git a/tests/utils_tests/test_safestring.py b/tests/utils_tests/test_safestring.py
new file mode 100644
index 0000000000..a6f0c0a01c
--- /dev/null
+++ b/tests/utils_tests/test_safestring.py
@@ -0,0 +1,53 @@
+from __future__ import absolute_import, unicode_literals
+
+
+from django.template import Template, Context
+from django.test import TestCase
+from django.utils.encoding import force_text, force_bytes
+from django.utils.functional import lazy, Promise
+from django.utils.html import escape, conditional_escape
+from django.utils.safestring import mark_safe, mark_for_escaping
+from django.utils import six
+from django.utils import translation
+
+lazystr = lazy(force_text, six.text_type)
+lazybytes = lazy(force_bytes, bytes)
+
+
+class SafeStringTest(TestCase):
+    def assertRenderEqual(self, tpl, expected, **context):
+        context = Context(context)
+        tpl = Template(tpl)
+        self.assertEqual(tpl.render(context), expected)
+
+    def test_mark_safe(self):
+        s = mark_safe('a&b')
+
+        self.assertRenderEqual('{{ s }}', 'a&b', s=s)
+        self.assertRenderEqual('{{ s|force_escape }}', 'a&amp;b', s=s)
+
+    def test_mark_safe_lazy(self):
+        s = lazystr('a&b')
+        b = lazybytes(b'a&b')
+
+        self.assertIsInstance(mark_safe(s), Promise)
+        self.assertIsInstance(mark_safe(b), Promise)
+        self.assertRenderEqual('{{ s }}', 'a&b', s=mark_safe(s))
+
+    def test_mark_for_escaping(self):
+        s = mark_for_escaping('a&b')
+        self.assertRenderEqual('{{ s }}', 'a&amp;b', s=s)
+        self.assertRenderEqual('{{ s }}', 'a&amp;b', s=mark_for_escaping(s))
+
+    def test_mark_for_escaping_lazy(self):
+        s = lazystr('a&b')
+        b = lazybytes(b'a&b')
+
+        self.assertIsInstance(mark_for_escaping(s), Promise)
+        self.assertIsInstance(mark_for_escaping(b), Promise)
+        self.assertRenderEqual('{% autoescape off %}{{ s }}{% endautoescape %}', 'a&amp;b', s=mark_for_escaping(s))
+
+    def test_regression_20296(self):
+        s = mark_safe(translation.ugettext_lazy("username"))
+        with translation.override('fr'):
+            self.assertRenderEqual('{{ s }}', "nom d'utilisateur", s=s)