Normalize registered content types.

MIME content type strings are normalized by lower-casing the content
type parameters and then sorting them.  Each parameter is preceded by a
space.

docs/history.rst

@@ -9,6 +9,7 @@ Version History
 - Add :class:`sprockets.mixins.mediatype.transcoders.JSONTranscoder`
 - Add :class:`sprockets.mixins.mediatype.transcoders.MsgPackTranscoder`
 - Add :class:`sprockets.mixins.mediatype.transcoders.BinaryWrapper`
+- Normalize registered MIME types.
 
 `1.0.4`_ (14 Sep 2015)
 ----------------------

sprockets/mixins/mediatype/content.py

@@ -83,15 +83,18 @@ class ContentSettings(object):
         self.default_encoding = None
 
     def __getitem__(self, content_type):
-        return self._handlers[content_type]
+        parsed = headers.parse_content_type(content_type)
+        return self._handlers[str(parsed)]
 
     def __setitem__(self, content_type, handler):
+        parsed = headers.parse_content_type(content_type)
+        content_type = str(parsed)
         if content_type in self._handlers:
             logger.warning('handler for %s already set to %r',
                            content_type, self._handlers[content_type])
             return
 
-        self._available_types.append(headers.parse_content_type(content_type))
+        self._available_types.append(parsed)
         self._handlers[content_type] = handler
 
     def get(self, content_type, default=None):

tests.py

@@ -194,6 +194,26 @@ class ContentSettingsTests(unittest.TestCase):
         settings['application/json'] = object()
         self.assertIs(settings.get('application/json'), handler)
 
+    def test_that_registered_content_types_are_normalized(self):
+        settings = content.ContentSettings()
+        handler = object()
+        settings['application/json; VerSion=foo; type=WhatEver'] = handler
+        self.assertIs(settings['application/json; type=whatever; version=foo'],
+                      handler)
+        self.assertIn('application/json; type=whatever; version=foo',
+                      (str(c) for c in settings.available_content_types))
+
+    def test_that_normalized_content_types_do_not_overwrite(self):
+        settings = content.ContentSettings()
+        settings['application/json; charset=UTF-8'] = handler = object()
+        settings['application/json; charset=utf-8'] = object()
+        self.assertEqual(len(settings.available_content_types), 1)
+        self.assertEqual(settings.available_content_types[0].content_type,
+                         'application')
+        self.assertEqual(settings.available_content_types[0].content_subtype,
+                         'json')
+        self.assertEqual(settings['application/json; charset=utf-8'], handler)
+
 
 class ContentFunctionTests(unittest.TestCase):