diff --git a/zaza/openstack/charm_tests/vault/tests.py b/zaza/openstack/charm_tests/vault/tests.py
index 99f38725f..cb117815f 100644
--- a/zaza/openstack/charm_tests/vault/tests.py
+++ b/zaza/openstack/charm_tests/vault/tests.py
@@ -19,6 +19,7 @@
 import contextlib
 import json
 import logging
+import subprocess
 import unittest
 import uuid
 
@@ -350,5 +351,78 @@ def test_vault_restart(self):
         self.assertTrue(lead_client.hvac_client.seal_status['sealed'])
 
 
+class VaultCacheTest(BaseVaultTest):
+    """Encapsulate vault tests."""
+
+    @test_utils.skipIfNotHA('vault')
+    def test_vault_caching_unified_view(self):
+        """Verify that the vault applicate presents consisent certificates.
+
+        On all of the relations to the clients.
+        """
+        try:
+            application = zaza.model.get_application('keystone')
+        except KeyError:
+            self.skipTest("Application 'keystone' not available so skipping.")
+        # data keys that are 'strs'
+        key_str_values = ['ca', 'chain', 'client.cert', 'client.key']
+        for unit in application.units:
+            command = ['juju', 'show-unit', '--format=json', unit.entity_id]
+            output = subprocess.check_output(command).decode()
+            unit_info = json.loads(output)
+            # verify that unit_info{unit.entity_id}{'relation-info'}[n],
+            # where List item [n] is a {} where,
+            # [n]{'endpoint'} == 'certificates' AND
+            # [n]{'related_units'}{*}{'data'}{...} all match.
+            #
+            # first collect the list items that are 'certificates' endpoint.
+            relation_info_list = [
+                item
+                for item in unit_info[unit.entity_id]['relation-info']
+                if item['endpoint'] == 'certificates']
+            # collect the data for each of the units.
+            unit_data_list = [
+                {key: value['data']
+                 for key, value in item['related-units'].items()}
+                for item in relation_info_list]
+            # for each str key, verify that it's the same string on all lists.
+            for str_key in key_str_values:
+                values = set((v[str_key]
+                              for unit_data in unit_data_list
+                              for v in unit_data.values()))
+                self.assertEqual(len(values), 1,
+                                 "Not all {} items in data match: {}"
+                                 .format(str_key, "\n".join(values)))
+            # now validate that 'processed_requests' are the same.
+            # they are json encoded, so need pulling out of the json; first get
+            # the keys that look like "keystone_0.processed_requests".
+            data_keys = set((k
+                             for u in unit_data_list
+                             for v in u.values()
+                             for k in v.keys()))
+            processed_request_keys = [
+                k for k in data_keys if k.endswith(".processed_requests")]
+            # now for each processed_request keys, fetch the associated databag
+            # and json.loads it to get the values; they should match across the
+            # relations. Using json.loads just in case the ordering of the
+            # json.dumps is not determined.
+            for processed_request_key in processed_request_keys:
+                data_bags = [
+                    (unit, json.loads(v[processed_request_key]))
+                    for u in unit_data_list
+                    for unit, v in u.items()]
+                # data_bags: [(unit, processed_requests dict)]
+                self.assertGreater(
+                    len(data_bags), 1,
+                    "Key {} is only in one bag".format(processed_request_key))
+                first_bag = data_bags[0]
+                for data_bag in data_bags[1:]:
+                    self.assertEqual(
+                        first_bag[1], data_bag[1],
+                        "key {}: bag for: {} doesn't match bag for: {}"
+                        .format(
+                            processed_request_key, first_bag[0], data_bag[0]))
+
+
 if __name__ == '__main__':
     unittest.main()