Add pool_client's methods and tests to Designate tempest plugin

Partially-Implements: blueprint designate-tempest-plugin

Change-Id: Id758b52d30018a7dea363979d167a879a57f09c7
diff --git a/designate_tempest_plugin/data_utils.py b/designate_tempest_plugin/data_utils.py
index 322e506..d3c72cc 100644
--- a/designate_tempest_plugin/data_utils.py
+++ b/designate_tempest_plugin/data_utils.py
@@ -196,3 +196,13 @@
     name = "*.{0}".format(zone_name)
     records = ["ns.example.com."]
     return rand_recordset_data('NS', zone_name, name, records)
+
+
+def rand_ns_records():
+    ns_zone = rand_zone_name()
+    records = []
+    for i in range(0, 2):
+        records.append("ns%s.%s" % (i, ns_zone))
+    ns_records = [{"hostname": x, "priority": random.randint(1, 999)}
+                  for x in records]
+    return ns_records