Remove unused exception

Remove unused VolumeDriverException and unused import in cinderlib.py

cinderlib/cinderlib.py

@@ -38,7 +38,6 @@ from oslo_utils import importutils
 import urllib3
 
 import cinderlib
-from cinderlib import exception
 from cinderlib import nos_brick
 from cinderlib import objects
 from cinderlib import persistence

cinderlib/exception.py

@@ -21,7 +21,6 @@ VolumeNotFound = exception.VolumeNotFound
 SnapshotNotFound = exception.SnapshotNotFound
 ConnectionNotFound = exception.VolumeAttachmentNotFound
 InvalidVolume = exception.InvalidVolume
-VolumeDriverException = exception.VolumeDriverException
 
 
 class InvalidPersistence(Exception):

cinderlib/tests/unit/test_cinderlib.py

@@ -37,8 +37,7 @@ class TestCinderlib(base.BaseTest):
         driver_cfg = {'k': 'v', 'k2': 'v2', 'volume_backend_name': 'Test'}
         cinderlib.Backend.global_initialization = False
         driver = mock_import.return_value
-        driver.get_volume_stats.return_value = {
-            'pools': [{'pool_name': 'default'}]}
+        driver.capabilities = {'pools': [{'pool_name': 'default'}]}
 
         backend = objects.Backend(**driver_cfg)
 
@@ -62,7 +61,7 @@ class TestCinderlib(base.BaseTest):
         driver.set_initialized.assert_called_once_with()
         self.assertEqual(driver_cfg, backend._driver_cfg)
         self.assertIsNone(backend._volumes)
-        driver.get_volume_stats.assert_called_once_with(refresh=False)
+        driver.get_volume_stats.assert_not_called()
         self.assertEqual(('default',), backend.pool_names)
 
     @mock.patch('urllib3.disable_warnings')