Add skip check for volume revert feature

Volume revert is a new feature added in microversion 3.40, and now not all
storage backend drivers have supported this feature. So it is necessary to
add a skip check for it in Tempest tests.

Change-Id: Icbd108f62f5b308e419843b03af20c8fe1278b24
diff --git a/cinder/tests/tempest/api/volume/test_volume_revert.py b/cinder/tests/tempest/api/volume/test_volume_revert.py
index 7314fdb..1f4bead 100644
--- a/cinder/tests/tempest/api/volume/test_volume_revert.py
+++ b/cinder/tests/tempest/api/volume/test_volume_revert.py
@@ -27,6 +27,12 @@
     min_microversion = '3.40'
 
     @classmethod
+    def skip_checks(cls):
+        super(VolumeRevertTests, cls).skip_checks()
+        if not CONF.volume_feature_enabled.volume_revert:
+            raise cls.skipException("Cinder volume revert feature disabled")
+
+    @classmethod
     def setup_clients(cls):
         cls._api_version = 3
         super(VolumeRevertTests, cls).setup_clients()
diff --git a/cinder/tests/tempest/config.py b/cinder/tests/tempest/config.py
index f4eb098..e15a399 100644
--- a/cinder/tests/tempest/config.py
+++ b/cinder/tests/tempest/config.py
@@ -19,4 +19,7 @@
     cfg.BoolOpt('consistency_group',
                 default=False,
                 help='Enable to run Cinder volume consistency group tests'),
+    cfg.BoolOpt('volume_revert',
+                default=False,
+                help='Enable to run Cinder volume revert tests'),
 ]