'Uses YAML file for cluster configuration if option given.
This is true even if the environment contains a valid configuration.'

def test_yaml_setup(self):

    tmpdir = tempfile.mkdtemp()
    self.addCleanup(shutil.rmtree, tmpdir)
    with open(os.path.join(tmpdir, 'cluster.yml'), 'wt') as f:
        f.write(_CLUSTER_YAML_CONTENTS)
    options = BenchmarkOptions()
    options.parseOptions(['--cluster', tmpdir])
    cluster = get_cluster(options, self.environ)
    self.assertEqual(cluster.control_node_address(), IPAddress(_YAML_CONTROL_SERVICE_ADDRESS))
