tweak Fn::GetAtt to return resource_json if resource is not implemented. DRY

This is better than failing out with a misleading Boto 400 error which should only happen when get_cfn_attribute is called but fails.

moto/sqs/models.py

@@ -4,7 +4,7 @@ import hashlib
 import time
 import re
 
-from boto.exception import BotoServerError
+
 from moto.core import BaseBackend
 from moto.core.utils import camelcase_to_underscores, get_random_message_id
 from .utils import generate_receipt_handle, unix_time_millis
@@ -154,13 +154,12 @@ class Queue(object):
         self._messages.append(message)
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'Arn':
             return self.queue_arn
         elif attribute_name == 'QueueName':
             return self.name
-        raise BotoServerError(400,
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
+        raise UnformattedGetAttTemplateException()
 
 
 class SQSBackend(BaseBackend):