Skip volume snapshot tests if feature is not enabled

Not all cinder volume backends support volume snapshot. For instance,
the default NFS backend doesn't. This patch adds a new entry to
CONF.volume_feature_enabled to add the possibility to skip volume
snapshot tests.

Change-Id: I40ce17924bbe4eb6f1c941df974bfa832ec2a999
diff --git a/etc/tempest.conf.sample b/etc/tempest.conf.sample
index 761a077..87f08f4 100644
--- a/etc/tempest.conf.sample
+++ b/etc/tempest.conf.sample
@@ -954,6 +954,9 @@
 # Runs Cinder volumes backup test (boolean value)
 #backup=true
 
+# Runs Cinder volume snapshot test (boolean value)
+#snapshot=true
+
 # A list of enabled volume extensions with a special entry all
 # which indicates every extension is enabled (list value)
 #api_extensions=all
diff --git a/tempest/api/volume/test_volumes_snapshots.py b/tempest/api/volume/test_volumes_snapshots.py
index 2ce3a4f..6294cd9 100644
--- a/tempest/api/volume/test_volumes_snapshots.py
+++ b/tempest/api/volume/test_volumes_snapshots.py
@@ -29,6 +29,9 @@
         super(VolumesSnapshotTest, cls).setUpClass()
         cls.volume_origin = cls.create_volume()
 
+        if not CONF.volume_feature_enabled.snapshot:
+            raise cls.skipException("Cinder volume snapshots are disabled")
+
     @classmethod
     def tearDownClass(cls):
         super(VolumesSnapshotTest, cls).tearDownClass()
diff --git a/tempest/api/volume/test_volumes_snapshots_negative.py b/tempest/api/volume/test_volumes_snapshots_negative.py
index 9e47c03..61aa307 100644
--- a/tempest/api/volume/test_volumes_snapshots_negative.py
+++ b/tempest/api/volume/test_volumes_snapshots_negative.py
@@ -14,13 +14,23 @@
 
 from tempest.api.volume import base
 from tempest.common.utils import data_utils
+from tempest import config
 from tempest import exceptions
 from tempest import test
 
+CONF = config.CONF
+
 
 class VolumesSnapshotNegativeTest(base.BaseVolumeV1Test):
     _interface = "json"
 
+    @classmethod
+    def setUpClass(cls):
+        super(VolumesSnapshotNegativeTest, cls).setUpClass()
+
+        if not CONF.volume_feature_enabled.snapshot:
+            raise cls.skipException("Cinder volume snapshots are disabled")
+
     @test.attr(type=['negative', 'gate'])
     def test_create_snapshot_with_nonexistent_volume_id(self):
         # Create a snapshot with nonexistent volume id
diff --git a/tempest/cli/simple_read_only/test_cinder.py b/tempest/cli/simple_read_only/test_cinder.py
index afbd732..723333b 100644
--- a/tempest/cli/simple_read_only/test_cinder.py
+++ b/tempest/cli/simple_read_only/test_cinder.py
@@ -16,6 +16,7 @@
 import logging
 import re
 import subprocess
+import testtools
 
 import tempest.cli
 from tempest import config
@@ -86,6 +87,8 @@
     def test_cinder_rate_limits(self):
         self.cinder('rate-limits')
 
+    @testtools.skipUnless(CONF.volume_feature_enabled.snapshot,
+                          'Volume snapshot not available.')
     def test_cinder_snapshot_list(self):
         self.cinder('snapshot-list')
 
diff --git a/tempest/config.py b/tempest/config.py
index b0945bb..be2a137 100644
--- a/tempest/config.py
+++ b/tempest/config.py
@@ -453,6 +453,9 @@
     cfg.BoolOpt('backup',
                 default=True,
                 help='Runs Cinder volumes backup test'),
+    cfg.BoolOpt('snapshot',
+                default=True,
+                help='Runs Cinder volume snapshot test'),
     cfg.ListOpt('api_extensions',
                 default=['all'],
                 help='A list of enabled volume extensions with a special '
diff --git a/tempest/scenario/test_stamp_pattern.py b/tempest/scenario/test_stamp_pattern.py
index 128ec17..5235871 100644
--- a/tempest/scenario/test_stamp_pattern.py
+++ b/tempest/scenario/test_stamp_pattern.py
@@ -50,6 +50,13 @@
     14. Check the existence of a file which created at 6. in volume2
     """
 
+    @classmethod
+    def setUpClass(cls):
+        super(TestStampPattern, cls).setUpClass()
+
+        if not CONF.volume_feature_enabled.snapshot:
+            raise cls.skipException("Cinder volume snapshots are disabled")
+
     def _wait_for_volume_snapshot_status(self, volume_snapshot, status):
         self.status_timeout(self.volume_client.volume_snapshots,
                             volume_snapshot.id, status)
diff --git a/tempest/scenario/test_volume_boot_pattern.py b/tempest/scenario/test_volume_boot_pattern.py
index e89ea70..faca31f 100644
--- a/tempest/scenario/test_volume_boot_pattern.py
+++ b/tempest/scenario/test_volume_boot_pattern.py
@@ -35,6 +35,12 @@
      * Boot an additional instance from the new snapshot based volume
      * Check written content in the instance booted from snapshot
     """
+    @classmethod
+    def setUpClass(cls):
+        super(TestVolumeBootPattern, cls).setUpClass()
+
+        if not CONF.volume_feature_enabled.snapshot:
+            raise cls.skipException("Cinder volume snapshots are disabled")
 
     def _create_volume_from_image(self):
         img_uuid = CONF.compute.image_ref