fix issue #173 Session cookie expiration isn't locale-safe (#174)

* fix issue #173 Session cookie expiration isn't locale-safe

.travis.yml

@@ -2,6 +2,11 @@ language: python
 os:
   - linux
 dist: xenial
+addons:
+  apt:
+    packages:
+      - language-pack-it
+      - locales
 services:
   - mongodb
   - memcached

beaker/session.py

@@ -9,6 +9,12 @@
 from beaker.exceptions import BeakerException, InvalidCryptoBackendError
 from beaker.cookie import SimpleCookie
 
+
+months = (None, "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+          "Jul", "Aug", "Sep", "Oct", "Nov", "Dec")
+weekdays = ("Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun")
+
+
 __all__ = ['SignedCookie', 'Session', 'InvalidSignature']
 
 
@@ -281,6 +287,13 @@ def _set_cookie_values(self, expires=None):
 
         self._set_cookie_expires(expires)
 
+    @staticmethod
+    def serialize_cookie_date(v):
+        v = v.timetuple()
+        r = time.strftime("%%s, %d-%%s-%Y %H:%M:%S GMT", v)
+        return r % (weekdays[v[6]], months[v[1]])
+
+
     def _set_cookie_expires(self, expires):
         if expires is None:
             expires = self.cookie_expires
@@ -300,7 +313,7 @@ def _set_cookie_expires(self, expires):
             self.cookie[self.key]['expires'] = ''
             return True
         self.cookie[self.key]['expires'] = \
-            expires_date.strftime("%a, %d-%b-%Y %H:%M:%S GMT")
+            self.serialize_cookie_date(expires_date)
         return expires_date
 
     def _update_cookie_out(self, set_cookie=True):

tests/test_cookie_expires.py

@@ -56,6 +56,17 @@ def test_cookie_exprires_2():
 
     assert no_expires is False, no_expires
 
+def test_cookie_expires_different_locale():
+    from locale import setlocale, LC_TIME
+    expires_date = datetime.datetime(2019, 5, 22)
+    setlocale(LC_TIME, 'it_IT.UTF-8')
+    # if you get locale.Error: unsupported locale setting. you have to enable that locale in your OS.
+    assert expires_date.strftime("%a, %d-%b-%Y %H:%M:%S GMT").startswith('mer,')
+    session = Session({}, cookie_expires=True, validate_key='validate_key')
+    assert session._set_cookie_expires(expires_date)
+    expires = cookie_expiration(session)
+    assert expires == 'Wed, 22-May-2019 00:00:00 GMT', expires
+    setlocale(LC_TIME, '')  # restore default locale for further tests
 
 def test_set_cookie_expires():
     """Exhibit Set-Cookie: values."""