go-tcptestを使って、echoサーバをテストする ref: http://qiita.com/uchiko/items/240d6c5d56c15027907a

echoserver.go

package echoserver

import (
        "bufio"
        "fmt"
        "net"
        "strconv"
)

type Server struct {
        Host string
        Port int
}

func (s *Server) Run() error {
        server, err := net.Listen("tcp", s.Host+":"+strconv.Itoa(s.Port))
        if err != nil {
                return err
        }
        conns := s.ClientConns(server)
        for {
                go s.HandleConn(<-conns)
        }
        return nil
}

func (s *Server) ClientConns(listener net.Listener) chan net.Conn {
        ch := make(chan net.Conn)
        i := 0
        go func() {
                for {
                        client, err := listener.Accept()
                        if err != nil {
                                fmt.Printf("couldn't accept: " + err.Error())
                                continue
                        }
                        i++
                        fmt.Printf("%d: %v <-> %v\n", i, client.LocalAddr(), client.RemoteAddr())
                        ch <- client
                }
        }()
        return ch
}

func (s *Server) HandleConn(client net.Conn) {
        b := bufio.NewReader(client)
        for {
                line, err := b.ReadBytes('\n')
                if err != nil { // EOF, or worse
                        break
                }
                client.Write(line)
        }
}

echoserver_test.go

package echoserver

import (
        "bufio"
        "fmt"
        "github.com/lestrrat/go-tcptest"
        "log"
        "net"
        "strconv"
        "testing"
        "time"
)

func TestRun(t *testing.T) {
        echo := func(port int) {
                server := &Server{Host: "localhost", Port: port}
                err := server.Run()
                if err != nil {
                        t.Error("Error")
                }
        }

        server, err := tcptest.Start(echo, 30*time.Second)
        if err != nil {
                t.Error("Failed to start echoserver: %s", err)
        }

        log.Printf("echoserver started on port %d", server.Port())

        conn, err := net.Dial("tcp", "localhost:"+strconv.Itoa(server.Port()))
        if err != nil {
                t.Error("Failed to connect to echoserver")
        }
        fmt.Fprintf(conn, "test hogehoge\n")
        res, err := bufio.NewReader(conn).ReadString('\n')
        if res != "test hogehoge\n" {
                t.Error("Wrong Response")
        }
}