Golang Gorilla Websocket Client Test Cases [duplicate] - go

I need to write unit test cases for Gorilla Web-socket.
var upgrader = websocket.Upgrader{} // use default options
func socketHandler(w http.ResponseWriter, r *http.Request) {
// Upgrade our raw HTTP connection to a websocket based one
conn, err := upgrader.Upgrade(w, r, nil)
if err != nil {
log.Print("Error during connection upgradation:", err)
return
}
defer conn.Close()
// The event loop
for {
messageType, message, err := conn.ReadMessage()
if err != nil {
log.Println("Error during message reading:", err)
break
}
log.Printf("Received: %s", message)
err = conn.WriteMessage(messageType, message)
if err != nil {
log.Println("Error during message writing:", err)
break
}
}
}
func home(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "Index Page")
}
func main() {
http.HandleFunc("/socket", socketHandler)
http.HandleFunc("/", home)
log.Fatal(http.ListenAndServe("localhost:8080", nil))
}
I want to write the Unit Test case for socketHandler function. How should I go about it?

Spin up an httptest.Server with the websocket endpoint. Dial the server with the websocket client. Send and receive messages as needed.
Here's a simple example:
func TestWs(t *testing.T) {
s := httptest.NewServer(http.HandlerFunc(socketHandler))
defer s.Close()
wsURL := "ws" + strings.TrimPrefix(s.URL, "http")
c, _, err := websocket.DefaultDialer.Dial(wsURL, nil)
if err != nil {
t.Error(err)
}
defer c.Close()
// Write a message.
c.WriteMessage(websocket.TextMessage, []byte("hello"))
// Expect the server to echo the message back.
c.SetReadDeadline(time.Now().Add(time.Second * 2))
mt, msg, err := c.ReadMessage()
if err != nil {
t.Error(err)
}
if mt != websocket.TextMessage || string(msg) != "hello" {
t.Errorf("expected text hello, got %d: %s", mt, msg)
}
}
Run the example on the playground.
To test a client, write a server endpoint that sends as receives messages as needed for a test. Run your client code against the endpoint as above.

Related

How to write Unit Test Cases for Gorilla Websocket

I need to write unit test cases for Gorilla Web-socket.
var upgrader = websocket.Upgrader{} // use default options
func socketHandler(w http.ResponseWriter, r *http.Request) {
// Upgrade our raw HTTP connection to a websocket based one
conn, err := upgrader.Upgrade(w, r, nil)
if err != nil {
log.Print("Error during connection upgradation:", err)
return
}
defer conn.Close()
// The event loop
for {
messageType, message, err := conn.ReadMessage()
if err != nil {
log.Println("Error during message reading:", err)
break
}
log.Printf("Received: %s", message)
err = conn.WriteMessage(messageType, message)
if err != nil {
log.Println("Error during message writing:", err)
break
}
}
}
func home(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "Index Page")
}
func main() {
http.HandleFunc("/socket", socketHandler)
http.HandleFunc("/", home)
log.Fatal(http.ListenAndServe("localhost:8080", nil))
}
I want to write the Unit Test case for socketHandler function. How should I go about it?
Spin up an httptest.Server with the websocket endpoint. Dial the server with the websocket client. Send and receive messages as needed.
Here's a simple example:
func TestWs(t *testing.T) {
s := httptest.NewServer(http.HandlerFunc(socketHandler))
defer s.Close()
wsURL := "ws" + strings.TrimPrefix(s.URL, "http")
c, _, err := websocket.DefaultDialer.Dial(wsURL, nil)
if err != nil {
t.Error(err)
}
defer c.Close()
// Write a message.
c.WriteMessage(websocket.TextMessage, []byte("hello"))
// Expect the server to echo the message back.
c.SetReadDeadline(time.Now().Add(time.Second * 2))
mt, msg, err := c.ReadMessage()
if err != nil {
t.Error(err)
}
if mt != websocket.TextMessage || string(msg) != "hello" {
t.Errorf("expected text hello, got %d: %s", mt, msg)
}
}
Run the example on the playground.
To test a client, write a server endpoint that sends as receives messages as needed for a test. Run your client code against the endpoint as above.

correct websocket connection closure

I wrote a connection closure function. It sends a closing frame and expects the same in response.
func TryCloseNormally(wsConn *websocket.Conn) error {
closeNormalClosure := websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")
defer wsConn.Close()
if err := wsConn.WriteControl(websocket.CloseMessage, closeNormalClosure, time.Now().Add(time.Second)); err != nil {
return err
}
if err := wsConn.SetReadDeadline(time.Now().Add(time.Second)); err != nil {
return err
}
_, _, err := wsConn.ReadMessage()
if websocket.IsCloseError(err, websocket.CloseNormalClosure) {
return nil
} else {
return errors.New("Websocket doesn't send a close frame in response")
}
}
I wrote a test for this function.
func TestTryCloseNormally(t *testing.T) {
done := make(chan struct{})
exit := make(chan struct{})
ctx := context.Background()
ln, err := net.Listen("tcp", "localhost:")
require.Nil(t, err)
handler := HandlerFunc(func(conn *websocket.Conn) {
for {
_, _, err := conn.ReadMessage()
if err != nil {
require.True(t, websocket.IsCloseError(err, websocket.CloseNormalClosure), err.Error())
return
}
}
})
s, err := makeServer(ctx, handler)
require.Nil(t, err)
go func() {
require.Nil(t, s.Run(ctx, exit, ln))
close(done)
}()
wsConn, _, err := websocket.DefaultDialer.Dial(addr+strconv.Itoa(ln.Addr().(*net.TCPAddr).Port), nil) //nolint:bodyclose
require.Nil(t, err)
require.Nil(t, wsConn.WriteMessage(websocket.BinaryMessage, []byte{'o', 'k'}))
require.Nil(t, TryCloseNormally(wsConn))
close(exit)
<-done
}
To my surprise, it works correctly. Readmessage() reads the closing frame. But in the test, I don't write anything.
Is this happening at the gorilla/websocket level?
Did I write the function correctly? Maybe reading the response frame also happens at the gorilla level.
The function is mostly correct.
Websocket endpoints echo close messages unless the endpoint has already send a close message on its own. See Closing Handshake in the Websocket RFC for more details.
In the normal close scenario, an application should expect to receive a close message after sending a close message.
To handle the case where the peer sent a data message before the sending the close message, read and discard data messages until an error is returned.
func TryCloseNormally(wsConn *websocket.Conn) error {
defer wsConn.Close()
closeNormalClosure := websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")
if err := wsConn.WriteControl(websocket.CloseMessage, closeNormalClosure, time.Now().Add(time.Second)); err != nil {
return err
}
if err := wsConn.SetReadDeadline(time.Now().Add(time.Second)); err != nil {
return err
}
for {
_, _, err := wsConn.ReadMessage()
if websocket.IsCloseError(err, websocket.CloseNormalClosure) {
return nil
}
if err != nil {
return err
}
}
}

Simple server client communication not working

This seemingly simple example is not working as expected and I feel bad for asking but here goes:
There's a client that retries connecting to the server, sends a message, and then waits for a response:
func client() {
var conn net.Conn
var err error
// retry server until it is up
for {
conn, err = net.Dial("tcp", ":8081")
if err == nil {
break
}
log.Println(err)
time.Sleep(time.Second)
}
// write to server
_, err = conn.Write([]byte("request"))
if err != nil {
log.Println(err)
return
}
// block & read from server
var buf []byte
n, err := conn.Read(buf)
if err != nil {
log.Println(err)
return
}
log.Printf("From server: %s\n", buf[:n])
}
It connects to a server which for each connection, reads and interprets the sent data, and sends a response if needed:
func server() {
ln, _ := net.Listen("tcp", ":8081")
for {
conn, _ := ln.Accept()
go handleConn(conn)
}
}
func handleConn(conn net.Conn) {
var buf []byte
n, err := conn.Read(buf)
if err != nil {
return
}
log.Printf("Server got: %s\n", buf)
if string(buf[:n]) == "request" {
_, _ = conn.Write([]byte("response"))
}
}
All driven by the main function:
func main() {
go client()
server()
}
Error handling is omitted for brevity. The expected behavior is that the client will connect to the server and send the message "request" and then block on the read. The server receives "request" and sends the message "response" back to the same connection. The client unblock, prints the received message and exits. Instead, when the program is run, the following is printed:
2019/09/01 22:24:02 From server:
2019/09/01 22:24:02 Server got:
Suggesting that no data was exchanged, and that the client did not block.
The looping in client is strange!
The looping not make sense if read/write is out.
But the error is only this:
//var buf []byte <--- this read 0 bytes
buf := make([]byte, 1024)
n, err := conn.Read(buf)
A proposal for you:
package main
import (
"log"
"net"
"time"
)
func client() {
var conn net.Conn
var err error
// retry server until it is up
for {
log.Printf("Connecting...")
conn, err = net.Dial("tcp", ":8082")
if err != nil {
log.Println(err)
break
}
time.Sleep(time.Second)
// write to server
log.Printf("Writing...")
_, err = conn.Write([]byte("request"))
if err != nil {
log.Println(err)
return
}
// block & read from server
log.Printf("Reading...")
var buf []byte
n, err := conn.Read(buf)
if err != nil {
log.Println(err)
return
}
log.Printf("From server: %s\n", buf[:n])
}
}
func server() {
ln, _ := net.Listen("tcp", ":8082")
for {
conn, _ := ln.Accept()
go handleConn(conn)
}
}
func handleConn(conn net.Conn) {
buf := make([]byte, 1024)
n, err := conn.Read(buf)
if err != nil {
return
}
log.Printf("Server got: [%d bytes] %s\n", n, buf)
if string(buf[:n]) == "request" {
_, _ = conn.Write([]byte("response"))
}
conn.Close()
}
func main() {
go client()
server()
}

Closing a redis subscription and ending the go routine when websocket connection closes

I'm pushing events from a redis subscription to a client who is connected via websocket. I'm having trouble unsubscribing and exiting the redis go routine when the client disconnects the websocket.
Inspired by this post, here's what I have thus far. I'm able to receive subscription events and send messages to the client via websocket, but when the client closes the websocket and the defer close(done) code fires, my case b, ok := <-done: doesn't fire. It seems to be overloaded by the default case???
package api
import (
...
"github.com/garyburd/redigo/redis"
"github.com/gorilla/websocket"
)
func wsHandler(w http.ResponseWriter, r *http.Request) {
var upgrader = websocket.Upgrader{
ReadBufferSize: 1024,
WriteBufferSize: 1024,
}
conn, err := upgrader.Upgrade(w, r, nil)
if err != nil {
HandleError(w, err)
return
}
defer conn.Close()
done := make(chan bool)
defer close(done)
for {
var req WSRequest
err := conn.ReadJSON(&req)
if err != nil {
HandleWSError(conn, err)
return
}
defer conn.Close()
go func(done chan bool, req *WSRequest, conn *websocket.Conn) {
rc := redisPool.Get()
defer rc.Close()
psc := redis.PubSubConn{Conn: rc}
if err := psc.PSubscribe(req.chanName); err != nil {
HandleWSError(conn, err)
return
}
defer psc.PUnsubscribe()
for {
select {
case b, ok := <-done:
if !ok || b == true {
return
}
default:
switch v := psc.Receive().(type) {
case redis.PMessage:
err := handler(conn, req, v)
if err != nil {
HandleWSError(conn, err)
}
case redis.Subscription:
log.Printf("%s: %s %d\n", v.Channel, v.Kind, v.Count)
case error:
log.Printf("error in redis subscription; err:\n%v\n", v)
HandleWSError(conn, v)
default:
// do nothing...
log.Printf("unknown redis subscription event type; %s\n", reflect.TypeOf(v))
}
}
}
}(done, &req, conn)
}
}
Make these changes to break out of the read loop when done serving the websocket connection:
Maintain a slice of the Redis connections created for this websocket connection.
Unsubscribe all connections when done.
Modify the read loop to return when the subscription count is zero.
Here's the code:
func wsHandler(w http.ResponseWriter, r *http.Request) {
var upgrader = websocket.Upgrader{
ReadBufferSize: 1024,
WriteBufferSize: 1024,
}
conn, err := upgrader.Upgrade(w, r, nil)
if err != nil {
HandleError(w, err)
return
}
defer conn.Close()
// Keep slice of all connections. Unsubscribe all connections on exit.
var pscs []redis.PubSubConn
defer func() {
for _, psc := range rcs {
psc.Unsubscribe() // unsubscribe with no args unsubs all channels
}
}()
for {
var req WSRequest
err := conn.ReadJSON(&req)
if err != nil {
HandleWSError(conn, err)
return
}
rc := redisPool.Get()
psc := redis.PubSubConn{Conn: rc}
pscs = append(pscs, psc)
if err := psc.PSubscribe(req.chanName); err != nil {
HandleWSError(conn, err)
return
}
go func(req *WSRequest, conn *websocket.Conn) {
defer rc.Close()
for {
switch v := psc.Receive().(type) {
case redis.PMessage:
err := handler(conn, req, v)
if err != nil {
HandleWSError(conn, err)
}
case redis.Subscription:
log.Printf("%s: %s %d\n", v.Channel, v.Kind, v.Count)
if v.Count == 0 {
return
}
case error:
log.Printf("error in redis subscription; err:\n%v\n", v)
HandleWSError(conn, v)
default:
// do nothing...
log.Printf("unknown redis subscription event type; %s\n", reflect.TypeOf(v))
}
}
}(&req, conn)
}
}
The code in the question and this answer dial multiple Redis connections for each websocket client. A more typical and scalable approach is to share a single Redis pubsub connection across multiple clients. The typical approach may be appropriate for your application given the high-level description, but I am still unsure of what you are trying to do given the code in the question.

Golang websocket client, close connection after getting result

How I can implement this kind of scenario:
1.I have LoginHandler which receives some user data - email and signedXml:
func LoginHandler(c *gin.Context) {
var (
err error
data LoginPost
)
if err = c.BindJSON(&data); err != nil {
c.JSON(http.StatusBadRequest, gin.H{"status": "error"})
return
}
...
c.JSON(http.StatusOK, gin.H{"status": "ok"})
}
2.I need to send signedXml to another server via websocket
3.Save result (success or error)
4.Close connection
Every HTTP request will open connection, send 1 message, get 1 result and finally close socket. I was trying with channel, but no success. Is this possible to implement my case?
UPDATE
package main
import (
"log"
"net/url"
"github.com/gorilla/mux"
"github.com/gorilla/websocket"
"net/http"
)
func indexHandler(w http.ResponseWriter, r *http.Request) {
message := r.FormValue("message")
w.Write([]byte(message))
}
func postHandler(w http.ResponseWriter, r *http.Request) {
var (
message = r.FormValue("message")
u = url.URL{Scheme: "ws", Host: "echo.websocket.org", Path: "/"}
err error
out []byte
conn *websocket.Conn
)
log.Printf("message: %s\n", message)
log.Printf("connecting to %s\n", u.String())
conn, _, err = websocket.DefaultDialer.Dial(u.String(), nil)
if err != nil {
log.Fatal("dial:", err)
}
log.Println("write")
if err = conn.WriteMessage(websocket.TextMessage, []byte(message)); err != nil {
log.Fatal("write:", err)
}
log.Println("read")
if _, out, err = conn.ReadMessage(); err != nil {
log.Fatal("read:", err)
}
w.Write(out)
log.Println("close")
conn.Close()
}
func main() {
r := mux.NewRouter()
r.HandleFunc("/", indexHandler).Methods("GET")
r.HandleFunc("/post", postHandler).Methods("POST")
http.Handle("/", r)
http.ListenAndServe(":8080", nil)
}
Call Dial, WriteMessage, ReadMessage and Close in sequence.
c, _, err := websocket.DefaultDialer.Dial(url, nil)
if err != nil {
// handle error
}
err := c.WriteMessage(websocket.TextMessage, signedXML)
if err != nil {
// handle error
}
_, p, err := c.ReadMessage()
if err != nil {
// handle error
}
c.Close()
// p is a []byte with the first received message.

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