'Create known stores. Mock out sheepdog\'s subprocess dependency
on collie.
:param passing_config: making store driver passes basic configurations.
:returns: the number of how many store drivers been loaded.'

def _create_stores(self, passing_config=True):

    store.register_opts(CONF)
    self.config(default_store='filesystem', filesystem_store_datadir=self.test_dir, group='glance_store')
    store.create_stores(CONF)
