'Missing default policy file should result in a default ruleset'

def test_policy_file_default_not_found(self):

    def fake_find_file(self, name):
        return None
    self.stubs.Set(oslo_config.cfg.ConfigOpts, 'find_file', fake_find_file)
    enforcer = glance.api.policy.Enforcer()
    context = glance.context.RequestContext(roles=[])
    enforcer.enforce(context, 'get_image', {})
    self.assertRaises(exception.Forbidden, enforcer.enforce, context, 'manage_image_cache', {})
    admin_context = glance.context.RequestContext(roles=['admin'])
    enforcer.enforce(admin_context, 'manage_image_cache', {})
