          self.assertEquals(serializer.errors, {'content': [u'Ensure this value has at most 1000 characters (it has 1001).']})
  
  
  class MetadataTests(TestCase):
      def test_empty(self):
          serializer = CommentSerializer()
          expected = {
              'email': serializers.CharField,
 
</s> remove             return  # TODO Consider validation behaviour, 'required' opt etc...
 </s> add             if self.required:
                raise ValidationError(self.error_messages['required'])
            return </s> remove             return ModelField(model_field=model_field)
 </s> add             ret = ModelField(model_field=model_field)

        if model_field.default:
            ret.required = False

        return ret </s> remove             return field_mapping[model_field.__class__]()
 </s> add             ret = field_mapping[model_field.__class__]() </s> remove             self._data.pop(self._METHOD_PARAM)
 </s> add 
    def test_update_missing_field(self):
        data = {
            'content': 'xxx',
            'created': datetime.datetime(2012, 1, 1)
        }
        serializer = CommentSerializer(data, instance=self.comment)
        self.assertEquals(serializer.is_valid(), False)
        self.assertEquals(serializer.errors, {'email': [u'This field is required.']})

          self.assertEquals(serializer.errors, {'content': [u'Ensure this value has at most 1000 characters (it has 1001).']})
  
    def test_update_missing_field(self):
        data = {
            'content': 'xxx',
            'created': datetime.datetime(2012, 1, 1)
        }
        serializer = CommentSerializer(data, instance=self.comment)
        self.assertEquals(serializer.is_valid(), False)
        self.assertEquals(serializer.errors, {'email': [u'This field is required.']})

  
  class MetadataTests(TestCase):
      def test_empty(self):
          serializer = CommentSerializer()
          expected = {
              'email': serializers.CharField,
keep add keep keep keep keep keep keep
 Fix issue where required fields were not being properly validated.  Also make model fields with a default value be not required 
rest_framework/tests/serializer.py