dtest.client_request_metrics_test.TestClientRequestMetrics.test_client_request_metrics

https://ci-cassandra.apache.org/job/Cassandra-trunk/1459/testReport/dtest.client_request_metrics_test/TestClientRequestMetrics/test_client_request_metrics/
and
https://ci-cassandra.apache.org/job/Cassandra-trunk/1461/testReport/dtest-offheap.client_request_metrics_test/TestClientRequestMetrics/test_client_request_metrics/

Error Message
AttributeError: 'dict' object has no attribute 'scope'
Stacktrace
self = <client_request_metrics_test.TestClientRequestMetrics object at 0x7f0f53975460>

def test_client_request_metrics(self):

1. this is written as a single test method in order to reuse the same cluster for all tests
2. setup_once configures and starts the cluster with all schema and preconditions required by all tests.
   self.setup_once()

> self.write_nominal()

client_request_metrics_test.py:85:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
client_request_metrics_test.py:116: in write_nominal
global_diff, cl_diff = self.validate_nominal('Write',