Create a snapshot from a in-use volume with force=False

In order to test the interface of "force=False",
and distinguish with "force=True".
If the interface is "force=True",
we can create a snapshot from a in-use volume successfully.

Change-Id: I7a2002b274c8ccefc4e398c1ef362ebd7cdb1395
diff --git a/tempest/api/volume/test_volumes_snapshots.py b/tempest/api/volume/test_volumes_snapshots.py
index 8ffc99d..be3f1f2 100644
--- a/tempest/api/volume/test_volumes_snapshots.py
+++ b/tempest/api/volume/test_volumes_snapshots.py
@@ -16,6 +16,7 @@
 from tempest import config
 from tempest.lib.common.utils import data_utils
 from tempest.lib import decorators
+from tempest.lib import exceptions as lib_exc
 from tempest import test
 
 CONF = config.CONF
@@ -42,6 +43,10 @@
         server = self.create_server(wait_until='ACTIVE')
         self.attach_volume(server['id'], self.volume_origin['id'])
 
+        # Snapshot a volume which attached to an instance with force=False
+        self.assertRaises(lib_exc.BadRequest, self.create_snapshot,
+                          self.volume_origin['id'], force=False)
+
         # Snapshot a volume even if it's attached to an instance
         snapshot = self.create_snapshot(self.volume_origin['id'],
                                         force=True)