Add wscat task.

go.mod

@@ -9,11 +9,13 @@ require (
 	github.com/google/go-cmp v0.4.0
 	github.com/gorilla/handlers v1.4.2
 	github.com/gorilla/mux v1.7.4
+	github.com/gorilla/websocket v1.4.2
 	github.com/spf13/cobra v0.0.5
 	github.com/stretchr/testify v1.4.0
 	go.uber.org/goleak v1.0.0
 	golang.org/x/net v0.0.0-20190628185345-da137c7871d7
 	golang.org/x/perf v0.0.0-20191209155426-36b577b0eb03
+	golang.org/x/sync v0.0.0-20190423024810-112230192c58
 	golang.org/x/tools v0.0.0-20200125223703-d33eef8e6825
 	gopkg.in/yaml.v2 v2.2.8
 )

go.sum

@@ -32,6 +32,8 @@ github.com/gorilla/handlers v1.4.2 h1:0QniY0USkHQ1RGCLfKxeNHK9bkDHGRYGNDFBCS+YAR
 github.com/gorilla/handlers v1.4.2/go.mod h1:Qkdc/uu4tH4g6mTK6auzZ766c4CA0Ng8+o/OAirnOIQ=
 github.com/gorilla/mux v1.7.4 h1:VuZ8uybHlWmqV03+zRzdwKL4tUnIp1MAQtp1mIFE1bc=
 github.com/gorilla/mux v1.7.4/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
+github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
+github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=

wscat/README.md

@@ -0,0 +1,34 @@
+## wscat
+
+wscat - примитивный аналог npm пакета [wscat](https://www.npmjs.com/package/wscat).
+
+Websocket - это двусторониий канал поверх tcp. wscat - это websocket клиент.
+
+wscat принимает на вход единственный аргумент `-addr` - адрес websocket сервера.
+После подключения программа начинает читать с stdin'а и отправлять пользовательские строки на сервер,
+печатая все сообщения от сервера в stdout.
+
+Клиент должен обрабатывать SIGINT и SIGTERM и плавно завершаться с кодом 0 дожидаясь горутин.
+Для этого может пригодиться [context](https://golang.org/pkg/context/).
+
+Обратите внимание на то, что exit code `go run` - это не exit code исполняемого файла.
+
+## ПримерПрограмма
+
+Публичный echo сервер:
+```
+✗ $GOPATH/bin/wscat -addr ws://echo.websocket.org
+abc
+abcdef
+def^C2020/04/04 05:01:32 received signal interrupt
+```
+```
+✗ echo $?
+0
+```
+
+
+## Ссылки
+
+1. websocket: https://en.wikipedia.org/wiki/WebSocket
+2. signal shutdown: https://p.go.manytask.org/06-http/lecture.slide#20

wscat/main.go

@@ -0,0 +1,7 @@
+// +build !solution
+
+package main
+
+func main() {
+
+}

wscat/main_test.go

@@ -0,0 +1,144 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"log"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+	"testing"
+	"time"
+
+	"github.com/gorilla/websocket"
+	"github.com/stretchr/testify/require"
+
+	"gitlab.com/slon/shad-go/tools/testtool"
+)
+
+const importPath = "gitlab.com/slon/shad-go/wscat"
+
+var binCache testtool.BinCache
+
+func TestMain(m *testing.M) {
+	os.Exit(func() int {
+		var teardown testtool.CloseFunc
+		binCache, teardown = testtool.NewBinCache()
+		defer teardown()
+
+		return m.Run()
+	}())
+}
+
+type Conn struct {
+	in  io.WriteCloser
+	out *bytes.Buffer
+}
+
+func startCommand(t *testing.T, addr string) (conn *Conn, stop func()) {
+	t.Helper()
+
+	binary, err := binCache.GetBinary(importPath)
+	require.NoError(t, err)
+
+	cmd := exec.Command(binary, "-addr", addr)
+	cmd.Stderr = os.Stderr
+
+	out := &bytes.Buffer{}
+	cmd.Stdout = out
+
+	stdin, err := cmd.StdinPipe()
+	require.NoError(t, err)
+
+	require.NoError(t, cmd.Start())
+
+	conn = &Conn{
+		in:  stdin,
+		out: out,
+	}
+
+	done := make(chan struct{})
+	go func() {
+		_ = cmd.Wait()
+		close(done)
+	}()
+
+	stop = func() {
+		defer func() {
+			_ = cmd.Process.Kill()
+			<-done
+		}()
+
+		// try killing softly
+		_ = cmd.Process.Signal(syscall.SIGTERM)
+
+		ctx, cancel := context.WithTimeout(context.Background(), time.Millisecond*100)
+		defer cancel()
+
+		select {
+		case <-done:
+		case <-ctx.Done():
+			t.Fatalf("client shutdown timed out")
+		}
+	}
+
+	require.NoError(t, err)
+	return
+}
+
+func TestWScat(t *testing.T) {
+	upgrader := websocket.Upgrader{}
+
+	var received, sent [][]byte
+	h := func(w http.ResponseWriter, r *http.Request) {
+		c, err := upgrader.Upgrade(w, r, nil)
+		if err != nil {
+			log.Print("upgrade:", err)
+			return
+		}
+		defer func() { _ = c.Close() }()
+
+		for {
+			_, message, err := c.ReadMessage()
+			if err != nil {
+				t.Logf("error reading message: %s", err)
+				break
+			}
+			received = append(received, message)
+
+			resp := []byte(testtool.RandomName())
+			err = c.WriteMessage(websocket.TextMessage, resp)
+			require.NoError(t, err)
+			sent = append(sent, resp)
+		}
+	}
+
+	s := httptest.NewServer(http.HandlerFunc(h))
+	defer s.Close()
+
+	wsURL := strings.Replace(s.URL, "http", "ws", 1)
+	t.Logf("starting ws server %s", wsURL)
+
+	conn, stop := startCommand(t, wsURL)
+	defer stop()
+
+	var in [][]byte
+	for i := 0; i < 100; i++ {
+		msg := []byte(testtool.RandomName())
+		in = append(in, msg)
+
+		_, err := conn.in.Write(append(msg, '\n'))
+		require.NoError(t, err)
+	}
+
+	// give client time to make a request
+	time.Sleep(time.Millisecond * 100)
+	stop()
+
+	require.Equal(t, bytes.Join(in, nil), bytes.Join(received, nil))
+	require.Equal(t, bytes.Join(sent, nil), conn.out.Bytes())
+}