// returns nil for NOT_FOUND and  if volume exists
// still fails the test if driver for this volume is not vmdk
func volumeVmdkExists(t *testing.T, c *client.Client, vol string) *types.Volume {
	reply, err := c.VolumeList(context.Background(), filters.Args{})
	if err != nil {
		t.Fatalf("Failed to enumerate  volumes: %v", err)
	}

	for _, v := range reply.Volumes {
		//	t.Log(v.Name, v.Driver, v.Mountpoint)
		if v.Name == vol {
			return v
		}
	}
	return nil
}