Fix failed tests using Gossip protocol in Github Actions (0xPolygon#116)

* fix: add sleep before using gossip to build gossip network in test

* Add reference to comment for more information

e2e/broadcast_test.go

@@ -67,6 +67,9 @@ func TestBroadcast(t *testing.T) {
 				}
 			}
 
+			// wait until gossip protocol build mesh network (https://github.com/libp2p/specs/blob/master/pubsub/gossipsub/gossipsub-v1.0.md)
+			time.Sleep(time.Second * 2)
+
 			tx, err := signer.SignTx(&types.Transaction{
 				Nonce:    0,
 				From:     senderAddr,

network/gossip_test.go

@@ -1,13 +1,34 @@
 package network
 
 import (
+	"context"
+	"errors"
 	"testing"
 	"time"
 
 	testproto "github.com/0xPolygon/minimal/network/proto/test"
 	"github.com/stretchr/testify/assert"
 )
 
+func NumSubscribers(srv *Server, topic string) int {
+	return len(srv.ps.ListPeers(topic))
+}
+
+func WaitForSubscribers(ctx context.Context, srv *Server, topic string, expectedNumPeers int) error {
+	for {
+		if n := NumSubscribers(srv, topic); n >= expectedNumPeers {
+			return nil
+		}
+		select {
+		case <-ctx.Done():
+			return errors.New("canceled")
+		case <-time.After(100 * time.Millisecond):
+			continue
+		}
+	}
+
+}
+
 func TestGossip(t *testing.T) {
 	srv0 := CreateServer(t, nil)
 	srv1 := CreateServer(t, nil)
@@ -28,6 +49,11 @@ func TestGossip(t *testing.T) {
 		msgCh <- obj.(*testproto.AReq)
 	})
 
+	// wait until build mesh
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	WaitForSubscribers(ctx, srv0, topicName, 1)
+
 	// publish in topic0
 	assert.NoError(t, topic0.Publish(&testproto.AReq{Msg: "a"}))