Fix workaround for Django ticket 24240 in Python 3

c3ff8fb used the wrong utility function in its workaround for
https://code.djangoproject.com/ticket/24240, providing byte strings only
in Python 2. This commit switches to the correct function, and changes a
test to use the gzip middleware to show this is really fixed now.

mapit/shortcuts.py

@@ -8,7 +8,7 @@
 from django.shortcuts import get_object_or_404 as orig_get_object_or_404
 from django.template import loader
 from django.utils.six.moves import map
-from django.utils.encoding import smart_str
+from django.utils.encoding import smart_bytes
 from django.utils.translation import ugettext as _
 
 from mapit.iterables import defaultiter
@@ -54,7 +54,7 @@ def output_html(request, title, areas, **kwargs):
     areas = map(lambda area: item_tpl.render(Context({'area': area, 'indent_areas': indent_areas})), areas)
     areas = defaultiter(areas, '<li>' + _('No matching areas found.') + '</li>')
     content = itertools.chain(wraps[0:1], areas, wraps[1:])
-    content = map(smart_str, content)  # Workaround Django bug #24240
+    content = map(smart_bytes, content)  # Workaround Django bug #24240
 
     if django.get_version() >= '1.5':
         response_type = http.StreamingHttpResponse
@@ -76,7 +76,7 @@ def output_json(out, code=200):
         indent = 4
     encoder = GEOS_JSONEncoder(ensure_ascii=False, indent=indent)
     content = encoder.iterencode(out)
-    content = map(smart_str, content)  # Workaround Django bug #24240
+    content = map(smart_bytes, content)  # Workaround Django bug #24240
 
     types = {
         400: http.HttpResponseBadRequest,

mapit/tests/test_views.py

@@ -70,7 +70,7 @@ def test_areas_by_latlon(self):
 
     def test_areas_by_point(self):
         url = '/point/4326/-3.4,51.5.json'
-        response = self.client.get(url)
+        response = self.client.get(url, HTTP_ACCEPT_ENCODING='gzip')
 
         content = get_content(response)
 

mapit/tests/utils.py

@@ -1,10 +1,19 @@
 import json
+import zlib
 
 
 def get_content(response):
     if getattr(response, 'streaming', None):
         content = b''.join(response.streaming_content)
     else:
         content = response.content
+
+    # Just in case the response is gzipped
+    try:
+        # http://www.zlib.net/manual.html - add 16 to decode only the gzip format
+        content = zlib.decompress(content, 16+zlib.MAX_WBITS)
+    except zlib.error:
+        pass
+
     content = json.loads(content.decode('utf-8'))
     return content