add test for PythonItemExporter binary mode

scrapy/exporters.py

@@ -272,7 +272,11 @@ class PythonItemExporter(BaseItemExporter):
 
     def _serialize_dict(self, value):
         for key, val in six.iteritems(value):
+            key = to_bytes(key) if self.binary else key
             yield key, self._serialize_value(val)
 
     def export_item(self, item):
-        return dict(self._get_serialized_fields(item))
+        result = dict(self._get_serialized_fields(item))
+        if self.binary:
+            result = dict(self._serialize_dict(result))
+        return result

tests/test_exporters.py

@@ -2,6 +2,7 @@ from __future__ import absolute_import
 import re
 import json
 import unittest
+import warnings
 from io import BytesIO
 from six.moves import cPickle as pickle
 
@@ -115,6 +116,12 @@ class PythonItemExporterTest(BaseItemExporterTest):
         self.assertEqual(type(exported['age'][0]), dict)
         self.assertEqual(type(exported['age'][0]['age'][0]), dict)
 
+    def test_export_binary(self):
+        exporter = PythonItemExporter(binary=True)
+        value = TestItem(name=u'John\xa3', age=u'22')
+        expected = {b'name': b'John\xc2\xa3', b'age': b'22'}
+        self.assertEqual(expected, exporter.export_item(value))
+
 
 class PprintItemExporterTest(BaseItemExporterTest):