Fix skip checks in volume and snapshot manage tests

In volume and snapshot manage tests, misconfiguration of parameter
'manage_volume_ref' or 'manage_snapshot_ref' should lead the test
to fail, not skip the test. This patch is to raise InvalidConfiguration
exception when these two config parameters misconfigured.

Change-Id: I4038047e9ec734acdf01b5ece9962964f236ffdd
diff --git a/tempest/api/volume/admin/test_snapshot_manage.py b/tempest/api/volume/admin/test_snapshot_manage.py
index 6c09042..9ff7160 100644
--- a/tempest/api/volume/admin/test_snapshot_manage.py
+++ b/tempest/api/volume/admin/test_snapshot_manage.py
@@ -18,6 +18,7 @@
 from tempest import config
 from tempest.lib.common.utils import data_utils
 from tempest.lib import decorators
+from tempest.lib import exceptions
 
 CONF = config.CONF
 
@@ -38,8 +39,9 @@
             raise cls.skipException("Manage snapshot tests are disabled")
 
         if len(CONF.volume.manage_snapshot_ref) != 2:
-            raise cls.skipException("Manage snapshot ref is not correctly "
-                                    "configured")
+            msg = ("Manage snapshot ref is not correctly configured, "
+                   "it should be a list of two elements")
+            raise exceptions.InvalidConfiguration(msg)
 
     @decorators.idempotent_id('0132f42d-0147-4b45-8501-cc504bbf7810')
     def test_unmanage_manage_snapshot(self):
diff --git a/tempest/api/volume/admin/test_volume_manage.py b/tempest/api/volume/admin/test_volume_manage.py
index a039085..4b352e0 100644
--- a/tempest/api/volume/admin/test_volume_manage.py
+++ b/tempest/api/volume/admin/test_volume_manage.py
@@ -18,6 +18,7 @@
 from tempest import config
 from tempest.lib.common.utils import data_utils
 from tempest.lib import decorators
+from tempest.lib import exceptions
 
 CONF = config.CONF
 
@@ -32,8 +33,9 @@
             raise cls.skipException("Manage volume tests are disabled")
 
         if len(CONF.volume.manage_volume_ref) != 2:
-            raise cls.skipException("Manage volume ref is not correctly "
-                                    "configured")
+            msg = ("Manage volume ref is not correctly configured, "
+                   "it should be a list of two elements")
+            raise exceptions.InvalidConfiguration(msg)
 
     @decorators.idempotent_id('70076c71-0ce1-4208-a8ff-36a66e65cc1e')
     def test_unmanage_manage_volume(self):