Cleanup commit after peer review.

AUTHORS

@@ -58,6 +58,7 @@ answer newbie questions, and generally made Django that much better:
     Gisle Aas <gisle@aas.no>
     Chris Adams
     Mathieu Agopian <mathieu.agopian@gmail.com>
+    Roberto Aguilar <roberto@baremetal.io>
     ajs <adi@sieker.info>
     alang@bright-green.com
     A S Alam <aalam@users.sf.net>
@@ -651,7 +652,6 @@ answer newbie questions, and generally made Django that much better:
     Gasper Zejn <zejn@kiberpipa.org>
     Jarek Zgoda <jarek.zgoda@gmail.com>
     Cheng Zhang
-    Roberto Aguilar <roberto@baremetal.io>
 
 A big THANK YOU goes to:
 

django/core/serializers/__init__.py

@@ -17,7 +17,6 @@ To add your own serializers, use the SERIALIZATION_MODULES setting::
 """
 
 import importlib
-import sys
 
 from django.conf import settings
 from django.utils import six

tests/fixtures/tests.py

@@ -1,6 +1,5 @@
 from __future__ import unicode_literals
 
-import unittest
 import warnings
 
 from django.contrib.sites.models import Site

tests/serializers/tests.py

@@ -451,7 +451,7 @@ class YamlImportModuleMock(object):
     serializer is being imported.  The importlib.import_module() call is
     being made in the serializers.register_serializer().
 
-    #12756
+    Refs: #12756
     """
     def __init__(self):
         self._import_module = importlib.import_module
@@ -466,7 +466,7 @@ class YamlImportModuleMock(object):
 class NoYamlSerializerTestCase(TestCase):
     """Not having pyyaml installed provides a misleading error
 
-    #12756
+    Refs: #12756
     """
     @classmethod
     def setUpClass(cls):
@@ -489,7 +489,7 @@ class NoYamlSerializerTestCase(TestCase):
         # clear out cached serializers to clean out BadSerializer instances
         serializers._serializers = {}
 
-    def test_missing_pyyaml_error_message(self):
+    def test_serializer_pyyaml_error_message(self):
         """Using yaml serializer without pyyaml raises ImportError"""
         jane = Author(name="Jane")
         self.assertRaises(ImportError, serializers.serialize, "yaml", [jane])
@@ -498,7 +498,8 @@ class NoYamlSerializerTestCase(TestCase):
         """Using yaml deserializer without pyyaml raises ImportError"""
         self.assertRaises(ImportError, serializers.deserialize, "yaml", "")
 
-    def test_missing_pyyaml_error_message(self):
+    def test_dumpdata_pyyaml_error_message(self):
+        """Calling dumpdata produces an error when yaml package missing"""
         self.assertRaisesRegexp(management.CommandError, YAML_IMPORT_ERROR_MESSAGE,
                 management.call_command, 'dumpdata', format='yaml')
 

tests/serializers_regress/tests.py

@@ -523,7 +523,10 @@ def streamTest(format, self):
         else:
             self.assertEqual(string_data, stream.content.decode('utf-8'))
 
-for format in filter(lambda x: not isinstance(serializers.get_serializer(x), serializers.BadSerializer), serializers.get_serializer_formats()):
+for format in [
+            f for f in serializers.get_serializer_formats()
+            if not isinstance(serializers.get_serializer(f), serializers.BadSerializer)
+        ]:
     setattr(SerializerTests, 'test_' + format + '_serializer', curry(serializerTest, format))
     setattr(SerializerTests, 'test_' + format + '_natural_key_serializer', curry(naturalKeySerializerTest, format))
     setattr(SerializerTests, 'test_' + format + '_serializer_fields', curry(fieldsTest, format))