Allow skip of disk_config tests that require resize.

Change-Id: I6fc1441c2ba427d7cea83678c84e4342a2a46103
diff --git a/tempest/tests/compute/test_disk_config.py b/tempest/tests/compute/test_disk_config.py
index 6352f2d..fca83be 100644
--- a/tempest/tests/compute/test_disk_config.py
+++ b/tempest/tests/compute/test_disk_config.py
@@ -9,6 +9,8 @@
 
 class TestServerDiskConfig(unittest.TestCase):
 
+    resize_available = tempest.config.TempestConfig().compute.resize_available
+
     @classmethod
     def setUpClass(cls):
         cls.os = openstack.Manager()
@@ -125,6 +127,7 @@
 
     @attr(type='positive')
     @utils.skip_unless_attr('disk_config', 'Disk config extension not enabled')
+    @unittest.skipIf(not resize_available, 'Resize not available.')
     def test_resize_server_from_manual_to_auto(self):
         """A server should be resized from manual to auto disk config"""
         name = rand_name('server')
@@ -151,6 +154,7 @@
 
     @attr(type='positive')
     @utils.skip_unless_attr('disk_config', 'Disk config extension not enabled')
+    @unittest.skipIf(not resize_available, 'Resize not available.')
     def test_resize_server_from_auto_to_manual(self):
         """A server should be resized from auto to manual disk config"""
         name = rand_name('server')