testing rest-service proxy layer

i have a legacy web service system, we created rest proxy layer to convert that system into rest-service using spring MVC and for example

@Controller
@RequestMapping({ "/account" })
public class AccountProxyMapper extends AbstractProxyMapper {
    ...

i need to write integration tests that cover the new layer and to be added to continues integration server, i consumed too much time on searching about how to do so, is that applicable to have integration test script on a layer itself call services on another servers.