Tests: Fix coverage unit test failure
Tests: Fix coverage unit test failure

This fixes a failure in "tox -e cover"
due to a MagicMock being passed to dirname().

Change-Id: Ia3d9cdecb2567ae40bc61d5d1f7c33b607d3fbad

openstack/cinder,mahak/cinder,j-griffith/cinder,Datera/cinder,phenoxim/cinder,openstack/cinder,j-griffith/cinder,phenoxim/cinder,mahak/cinder,Datera/cinder