'verify that we can correctly discern a published item by ccx key'

def test_publication_api(self):

    with self.store.bulk_operations(self.ccx_locator):
        for expected in self.blocks:
            block_key = self.ccx_locator.make_usage_key(expected.location.block_type, expected.location.block_id)
            self.assertTrue(self.store.has_published_version(expected))
            self.store.unpublish(block_key, self.user.id)
            self.assertFalse(self.store.has_published_version(expected))
            self.store.publish(block_key, self.user.id)
            self.assertTrue(self.store.has_published_version(expected))
