Use mediatype.ContentMixin if its also extended

.gitignore

@@ -4,3 +4,4 @@ build
 dist
 env
 *.egg-info
+.coverage

docs/api.rst

@@ -79,9 +79,12 @@ exceptions will include the stack traces, etc.
 Standardized Error Response Documents
 -------------------------------------
 Version 0.5.0 also introduced the :class:`~sprockets.http.mixins.ErrorWriter`
-class which implements ``write_error`` to provide a standard JSON
-document response instead of the default HTML response that Tornado
-implements.
+class which implements ``write_error`` to provide a standard machine-readable
+document response instead of the default HTML response that Tornado implements.
+If :class:`~sprockets.mixins.mediatype.ContentMixin` is being used as well,
+``write_error`` will use
+:meth:`~sprockets.mixins.mediatype.ContentMixin.send_response` to send the
+document, otherwise it is sent as JSON.
 
 .. autoclass:: sprockets.http.mixins.ErrorWriter
    :members:

docs/history.rst

@@ -2,6 +2,9 @@
 
 Release History
 ===============
+`1.0.1`_ (20 Nov 2015)
+----------------------
+- Add support for ``sprockets.mixins.mediatype`` in ``sprockets.http.mixins.ErrorWriter``
 
 `1.0.0`_ (20 Nov 2015)
 ----------------------

requires/testing.txt

@@ -1 +1,2 @@
 nose>=1.3.1,<2
+mock>=1.3,<2

setup.py

@@ -2,7 +2,6 @@
 #
 
 import os.path
-import sys
 
 import setuptools
 

sprockets/http/__init__.py

@@ -1,7 +1,7 @@
 import os
 
 
-version_info = (1, 0, 0)
+version_info = (1, 0, 1)
 __version__ = '.'.join(str(v) for v in version_info)
 
 

sprockets/http/mixins.py

@@ -78,9 +78,14 @@ class ErrorWriter(object):
     """
     Write error bodies out consistently.
 
-    Mix this class in to your inheritance chain to include error
-    bodies as a standard JSON document.  The error document has
-    three simple properties:
+    Mix this class in to your inheritance chain to include error bodies in a
+    machine-readable document format.
+
+    If :class:`~sprockets.mixins.mediatype.ContentMixin` is also in use, it
+    will send the error response with it, otherwise the response is sent as
+    a JSON document.
+
+    The error document has three simple properties:
 
     **type**
         This is the type of exception that occurred or ``null``.
@@ -121,5 +126,9 @@ class ErrorWriter(object):
             reason = kwargs.get('reason', _get_http_reason(status_code))
             error_body.setdefault('message', reason)
 
-        self.set_header('Content-Type', 'application/json')
+        # If sprockets.mixins.media_type is being used, use it
+        if hasattr(self, 'send_response'):
+            self.send_response(error_body)
+        else:
+            self.set_header('Content-Type', 'application/json; charset=utf-8')
             self.write(json.dumps(error_body).encode('utf-8'))

tests.py

@@ -1,5 +1,6 @@
 import logging
 import json
+import mock
 
 from tornado import httputil, testing, web
 
@@ -161,3 +162,15 @@ class ErrorWriterTests(testing.AsyncHTTPTestCase):
 
         body = self._decode_response(response)
         self.assertGreater(len(body['traceback']), 0)
+
+    def test_that_mediatype_mixin_is_honored(self):
+        send_response = mock.Mock()
+        setattr(examples.StatusHandler, 'send_response', send_response)
+        response = self.fetch('/status/500')
+        self.assertEqual(response.code, 500)
+        send_response.assert_called_once_with({
+            'type': None,
+            'message': 'Internal Server Error',
+            'traceback': None
+        })
+        delattr(examples.StatusHandler, 'send_response')