Move common _delete_volume cleanup method in base compute test class

The test_volumes_get and test_volumes_list v2 compute tests were doing
similar volume cleanup.  This patch moves that code into the base class
so other tests that need to do volume cleanup, i.e. test_server_rescue,
can use it.

Related-Bug: #1254772

Change-Id: I59f4d638f8ab6e95736c78a384607ca89f1dcb67
diff --git a/tempest/api/compute/base.py b/tempest/api/compute/base.py
index 5539894..5e42919 100644
--- a/tempest/api/compute/base.py
+++ b/tempest/api/compute/base.py
@@ -227,6 +227,18 @@
         cls.password = server['adminPass']
         return server['id']
 
+    @classmethod
+    def delete_volume(cls, volume_id):
+        """Deletes the given volume and waits for it to be gone."""
+        try:
+            resp, _ = cls.volumes_extensions_client.delete_volume(volume_id)
+            # TODO(mriedem): We should move the wait_for_resource_deletion
+            # into the delete_volume method as a convenience to the caller.
+            cls.volumes_extensions_client.wait_for_resource_deletion(volume_id)
+        except exceptions.NotFound:
+            LOG.warn("Unable to delete volume '%s' since it was not found. "
+                     "Maybe it was already deleted?" % volume_id)
+
 
 class BaseV2ComputeAdminTest(BaseV2ComputeTest):
     """Base test case class for Compute Admin V2 API tests."""
diff --git a/tempest/api/compute/volumes/test_volumes_get.py b/tempest/api/compute/volumes/test_volumes_get.py
index b5a4802..b30f2f4 100644
--- a/tempest/api/compute/volumes/test_volumes_get.py
+++ b/tempest/api/compute/volumes/test_volumes_get.py
@@ -41,7 +41,7 @@
         resp, volume = self.client.create_volume(size=1,
                                                  display_name=v_name,
                                                  metadata=metadata)
-        self.addCleanup(self._delete_volume, volume)
+        self.addCleanup(self.delete_volume, volume['id'])
         self.assertEqual(200, resp.status)
         self.assertIn('id', volume)
         self.assertIn('displayName', volume)
@@ -69,16 +69,6 @@
                         'The fetched Volume metadata misses data '
                         'from the created Volume')
 
-    def _delete_volume(self, volume):
-        # Delete the Volume created in this method
-        try:
-            resp, _ = self.client.delete_volume(volume['id'])
-            self.assertEqual(202, resp.status)
-            # Checking if the deleted Volume still exists
-            self.client.wait_for_resource_deletion(volume['id'])
-        except KeyError:
-            return
-
 
 class VolumesGetTestXML(VolumesGetTestJSON):
     _interface = "xml"
diff --git a/tempest/api/compute/volumes/test_volumes_list.py b/tempest/api/compute/volumes/test_volumes_list.py
index ac89f99..7ce6216 100644
--- a/tempest/api/compute/volumes/test_volumes_list.py
+++ b/tempest/api/compute/volumes/test_volumes_list.py
@@ -59,7 +59,7 @@
                     # too small. So, here, we clean up whatever we did manage
                     # to create and raise a SkipTest
                     for volume in cls.volume_list:
-                        cls.client.delete_volume(volume)
+                        cls.delete_volume(volume['id'])
                     msg = ("Failed to create ALL necessary volumes to run "
                            "test. This typically means that the backing file "
                            "size of the nova-volumes group is too small to "
@@ -71,8 +71,7 @@
     def tearDownClass(cls):
         # Delete the created Volumes
         for volume in cls.volume_list:
-            resp, _ = cls.client.delete_volume(volume['id'])
-            cls.client.wait_for_resource_deletion(volume['id'])
+            cls.delete_volume(volume['id'])
         super(VolumesTestJSON, cls).tearDownClass()
 
     @attr(type='gate')