From 56b5bc0cc5c7400ed3700f9e469a422f2b849f61 Mon Sep 17 00:00:00 2001
From: Guilhem Fanton <8671905+gfanton@users.noreply.github.com>
Date: Fri, 3 May 2024 09:44:16 +0200
Subject: [PATCH] fix(gnodev): racy emitter test (#2022)

---
 contribs/gnodev/pkg/emitter/server.go      | 13 ++++++++++++-
 contribs/gnodev/pkg/emitter/server_test.go | 13 +++++++------
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/contribs/gnodev/pkg/emitter/server.go b/contribs/gnodev/pkg/emitter/server.go
index 68faf27122b..e6052890095 100644
--- a/contribs/gnodev/pkg/emitter/server.go
+++ b/contribs/gnodev/pkg/emitter/server.go
@@ -17,7 +17,7 @@ type Server struct {
 	logger    *slog.Logger
 	upgrader  websocket.Upgrader
 	clients   map[*websocket.Conn]struct{}
-	muClients sync.Mutex
+	muClients sync.RWMutex
 }
 
 func NewServer(logger *slog.Logger) *Server {
@@ -85,3 +85,14 @@ func (s *Server) emit(evt events.Event) {
 		}
 	}
 }
+
+func (s *Server) conns() []*websocket.Conn {
+	s.muClients.RLock()
+	conns := make([]*websocket.Conn, 0, len(s.clients))
+	for conn := range s.clients {
+		conns = append(conns, conn)
+	}
+	s.muClients.RUnlock()
+
+	return conns
+}
diff --git a/contribs/gnodev/pkg/emitter/server_test.go b/contribs/gnodev/pkg/emitter/server_test.go
index 6e1ba71b097..4725378dbda 100644
--- a/contribs/gnodev/pkg/emitter/server_test.go
+++ b/contribs/gnodev/pkg/emitter/server_test.go
@@ -5,6 +5,7 @@ import (
 	"net/http/httptest"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/gnolang/gno/contribs/gnodev/pkg/events"
 	"github.com/gnolang/gno/tm2/pkg/log"
@@ -21,8 +22,6 @@ func TestServer_New(t *testing.T) {
 }
 
 func TestServer_ServeHTTP(t *testing.T) {
-	t.Parallel()
-
 	svr := NewServer(log.NewTestingLogger(t))
 
 	s := httptest.NewServer(http.HandlerFunc(svr.ServeHTTP))
@@ -30,13 +29,15 @@ func TestServer_ServeHTTP(t *testing.T) {
 
 	u := "ws" + strings.TrimPrefix(s.URL, "http")
 	c, _, err := websocket.DefaultDialer.Dial(u, nil)
-	if err != nil {
-		t.Fatalf("client Dial failed: %v", err)
-	}
+	require.NoError(t, err, "client Dial failed")
+
 	defer c.Close()
 
+	assert.EventuallyWithT(t, func(c *assert.CollectT) {
+		assert.Len(c, svr.conns(), 1)
+	}, time.Second, time.Millisecond*100)
+
 	sendEvt := events.Custom("TEST")
-	assert.Len(t, svr.clients, 1)
 	svr.Emit(sendEvt) // simulate reload
 
 	var recvEvt eventJSON