added a (passing) test for ensuring the resolver gets shut down properly when it fails to resolve a domain.
added a (passing) test for ensuring the resolver gets shut down properly when it fails to resolve a domain.

yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx