'Wrapper utility that returns a test volume.
:param wait_until: wait till volume status.'

@classmethod
def create_volume(cls, wait_until='available', **kwargs):

    if ('size' not in kwargs):
        kwargs['size'] = CONF.volume.volume_size
    if ('imageRef' in kwargs):
        image = cls.images_client.show_image(kwargs['imageRef'])
        min_disk = image['min_disk']
        kwargs['size'] = max(kwargs['size'], min_disk)
    if ('name' not in kwargs):
        name = data_utils.rand_name((cls.__name__ + '-Volume'))
        kwargs['name'] = name
    volume = cls.volumes_client.create_volume(**kwargs)['volume']
    cls.volumes.append(volume)
    waiters.wait_for_volume_resource_status(cls.volumes_client, volume['id'], wait_until)
    return volume
