server.go

package main

import (
	"github.com/labstack/echo/v4"
	"golang.org/x/net/websocket"
)

func main() {
    
     //20200727
	e := echo.New()

	e.GET("/ws", func(c echo.Context) error {
    
    
		handler := websocket.Handler(func(conn *websocket.Conn) {
    
    
			readString(conn)

			conn.Write([]byte("ok"))
			println("send client : ok")
		})
		handler.ServeHTTP(c.Response().Writer, c.Request())
		return nil
	})
	e.Start(":11111")
}

func readString(conn *websocket.Conn) {
    
    
	var msg = make([]byte, 1024)
	read, err := conn.Read(msg)
	if err != nil {
    
    
		println(err)
	}
	println("from client : ", string(msg[:read]))
}

client_test.go

package main

import (
	"encoding/json"
	"golang.org/x/net/websocket"
	"testing"
)

var wsurl = "ws://localhost:11111/ws"
var origin = "ws://localhost:11111"

func TestSend(t *testing.T) {
    
     // 20200727

	ws, err := websocket.Dial(wsurl, "", origin)
	if err != nil {
    
    
		t.Log(err)
	}

	m := make(map[string]string)
	m["deviceId"] = "123"
	marshal, _ := json.Marshal(m)
	if err := websocket.Message.Send(ws, marshal); err != nil {
    
    
		t.Log(err)
	}
	t.Log("send server : ", m)
	data := make([]byte, 1024)
	n, err := ws.Read(data)
	if err != nil {
    
    
		t.Error(err)
	}
	t.Log("form server : ", string(data[:n]))
}