Skip tests when service barbican is enabled

We shouldn't run this tests when service Barbican enabled
because of they doesn't support Image Signature Verification.

This scenarios verifying in Barbican Tempest Plugin.

list of skipped tests:
tempest.scenario.test_snapshot_pattern.TestSnapshotPattern.test_snapshot_pattern
tempest.scenario.test_encrypted_cinder_volumes.TestEncryptedCinderVolumes.test_encrypted_cinder_volumes_luks
tempest.scenario.test_encrypted_cinder_volumes.TestEncryptedCinderVolumes.test_encrypted_cinder_volumes_cryptsetup
tempest.scenario.test_minimum_basic.TestMinimumBasicScenario.test_minimum_basic_scenario

Change-Id: I5db57b58ef0aaa10350e6f63e3f397f88e25df09
Related-prod: PROD-23370
(cherry picked from commit 9e46eb4e94aa08ba0235ca46c67baa47bf28ffe2)
diff --git a/tempest/scenario/test_encrypted_cinder_volumes.py b/tempest/scenario/test_encrypted_cinder_volumes.py
index 8c210d5..e2e54d2 100644
--- a/tempest/scenario/test_encrypted_cinder_volumes.py
+++ b/tempest/scenario/test_encrypted_cinder_volumes.py
@@ -13,6 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import testtools
+
 from tempest.common import utils
 from tempest import config
 from tempest.lib import decorators
@@ -54,6 +56,8 @@
 
     @decorators.idempotent_id('79165fb4-5534-4b9d-8429-97ccffb8f86e')
     @decorators.attr(type='slow')
+    @testtools.skipIf(getattr(CONF.service_available, 'barbican', False),
+                      'Image Signature Verification enabled')
     @utils.services('compute', 'volume', 'image')
     def test_encrypted_cinder_volumes_luks(self):
         server = self.launch_instance()
@@ -63,6 +67,8 @@
 
     @decorators.idempotent_id('cbc752ed-b716-4717-910f-956cce965722')
     @decorators.attr(type='slow')
+    @testtools.skipIf(getattr(CONF.service_available, 'barbican', False),
+                      'Image Signature Verification enabled')
     @utils.services('compute', 'volume', 'image')
     def test_encrypted_cinder_volumes_cryptsetup(self):
         server = self.launch_instance()
diff --git a/tempest/scenario/test_minimum_basic.py b/tempest/scenario/test_minimum_basic.py
index 2b35e45..5ecef44 100644
--- a/tempest/scenario/test_minimum_basic.py
+++ b/tempest/scenario/test_minimum_basic.py
@@ -13,6 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import testtools
+
 from tempest.common import custom_matchers
 from tempest.common import utils
 from tempest.common import waiters
@@ -99,6 +101,8 @@
                     return address
 
     @decorators.idempotent_id('bdbb5441-9204-419d-a225-b4fdbfb1a1a8')
+    @testtools.skipIf(getattr(CONF.service_available, 'barbican', False),
+                      'Image Signature Verification enabled')
     @utils.services('compute', 'volume', 'image', 'network')
     def test_minimum_basic_scenario(self):
         image = self.glance_image_create()
diff --git a/tempest/scenario/test_snapshot_pattern.py b/tempest/scenario/test_snapshot_pattern.py
index a33d4d4..5b62242 100644
--- a/tempest/scenario/test_snapshot_pattern.py
+++ b/tempest/scenario/test_snapshot_pattern.py
@@ -44,6 +44,8 @@
     @decorators.attr(type='slow')
     @testtools.skipUnless(CONF.network.public_network_id,
                           'The public_network_id option must be specified.')
+    @testtools.skipIf(getattr(CONF.service_available, 'barbican', False),
+                      'Image Signature Verification enabled')
     @utils.services('compute', 'network', 'image')
     def test_snapshot_pattern(self):
         # prepare for booting an instance