Add IE support for cookie deletion. (#994)

* Add IE support for cookie deletion.

IE<=11 ( !!! ) doesn't support the MaxAge property for cookies so del_cookie() also needs to set the Expires cookie header to support IE. Uses the UTC epoch for a standard expire time.

* Add IE support for cookie deletion. Style and test fixes.

* Add IE support for cookie deletion. Documentation updates.

* Add IE support for cookie deletion. Python 3.4 related test fixes.

* Add IE support for cookie deletion. set_cookie correction.

aiohttp/web_reqrep.py

@@ -511,8 +511,12 @@ def set_cookie(self, name, value, *, expires=None,
 
         self._cookies[name] = value
         c = self._cookies[name]
+
         if expires is not None:
             c['expires'] = expires
+        elif c.get('expires') == 'Thu, 01 Jan 1970 00:00:00 GMT':
+            del c['expires']
+
         if domain is not None:
             c['domain'] = domain
 
@@ -537,7 +541,9 @@ def del_cookie(self, name, *, domain=None, path='/'):
         """
         # TODO: do we need domain/path here?
         self._cookies.pop(name, None)
-        self.set_cookie(name, '', max_age=0, domain=domain, path=path)
+        self.set_cookie(name, '', max_age=0,
+                        expires="Thu, 01 Jan 1970 00:00:00 GMT",
+                        domain=domain, path=path)
 
     @property
     def content_length(self):

docs/web_reference.rst

@@ -504,6 +504,11 @@ StreamResponse
 
       :param str path: optional cookie path, ``'/'`` by default
 
+      .. versionchanged:: 0.23
+
+         Fixed cookie expiration support for
+         Internet Explorer (version less than 11).
+
    .. attribute:: content_length
 
       *Content-Length* for outgoing response.

tests/test_web_response.py

@@ -453,7 +453,8 @@ def test_response_cookies():
             'Set-Cookie: name=another_other_value; Max-Age=10; Path=/')
 
     resp.del_cookie('name')
-    expected = 'Set-Cookie: name=("")?; Max-Age=0; Path=/'
+    expected = ('Set-Cookie: name=("")?; '
+                'expires=Thu, 01 Jan 1970 00:00:00 GMT; Max-Age=0; Path=/')
     assert re.match(expected, str(resp.cookies))
 
     resp.set_cookie('name', 'value', domain='local.host')
@@ -491,7 +492,8 @@ def test_response_cookie__issue_del_cookie():
     assert str(resp.cookies) == ''
 
     resp.del_cookie('name')
-    expected = 'Set-Cookie: name=("")?; Max-Age=0; Path=/'
+    expected = ('Set-Cookie: name=("")?; '
+                'expires=Thu, 01 Jan 1970 00:00:00 GMT; Max-Age=0; Path=/')
     assert re.match(expected, str(resp.cookies))
 
 
@@ -502,6 +504,7 @@ def test_cookie_set_after_del():
     resp.set_cookie('name', 'val')
     # check for Max-Age dropped
     expected = 'Set-Cookie: name=val; Path=/'
+    print(expected)
     assert str(resp.cookies) == expected